This was CNBC's live blog tracking developments on the war in Ukraine.

Relations between Russia and China have reached an "unprecedented" level, Russian Foreign Minister Sergei Lavrov said Tuesday following talks with his Chinese counterpart in Beijing.

Lavrov said cooperation between the nations "exceeds ... the military-political alliances of the Cold War, and is not directed against any third party."

In other news, Russian authorities are scrambling to deal with massive flooding in the south of the country, with thousands of homes flooded after the Ural River, Europe's third-longest river, burst through a dam last Friday.

Floodwaters are expected to rise today in the Orenburg region, putting parts of the region's capital at risk, Russian news agencies reported.

Civilian deaths and injuries in Ukraine sharply increased in March, UN human rights body says

Deaths and injuries amongst civilians in Ukraine jumped 20% in March of this year compared to February, the United Nations human rights body said in a report Tuesday.

At least 604 civilians were killed or injured during the month, the UN Human Rights Monitoring Mission in Ukraine found. This includes at least 57 children, doubling the number when compared to the previous month, it added.

"The March increase in civilian casualties was mainly due to attacks by the Russian armed forces using missiles and loitering munitions across Ukraine and increased aerial bombardments near the frontline," the report said.

— Sophie Kiderlin

Russia has not been invited to Ukraine summit in Switzerland, embassy says

Russia has not been invited to the planned Ukraine summit in Switzerland, a spokesperson for the Russian embassy in Switzerland confirmed to CNBC.

"The Swiss side did not send Russia an invitation to the conference. At the same time, our position is well known. Even if we receive an invitation to such an event, the Russian side will not accept it," Vladimir Khokhlov, press secretary at the embassy said.

This is in line with comments previously made by Russian spokespeople, who have said the country would not join the proposed summit and that it was doomed to fail without Moscow's participation.

"The idea of a 'peace conference' promoted by the organizers is inappropriate for us, as it is just another variant of pushing through an unviable 'peace formula' that does not take into account Russian concerns," Khokhlov added.

Ukrainian President Volodymyr Zelenskyy and his allies have been working on plans for a Ukraine summit in Switzerland, which would see leaders discuss potential conflict resolution approaches. The talks would likely include Zelenskyy's 10-point peace formula.

According to Reuters, Zelenskyy over the weekend said a date for the summit could be agreed upon in the coming days or weeks and that 80 to 100 countries would participate.

— Sophie Kiderlin

Two killed by Ukrainian shelling on Russian village, local governor says

A woman and a child were killed by Ukrainian shelling in the Russian village of Klimovo, the local governor Aleksandr Bogomaz said in a post on Telegram on Tuesday, which was Google-translated by CNBC.

Three other civilians were injured and were receiving medical support, while several cars were injured and a fire broke out in a residential building due to the strike, he added. Klimovo is located in western Russia, near the border to both Ukraine and Belarus.

CNBC could not independently verify the report.

— Sophie Kiderlin

Russia, Kazakhstan evacuate over 100,000 people amid worst flooding in decades

Russia and Kazakhstan ordered more than 100,000 people to evacuate after swiftly melting snow swelled mighty rivers beyond bursting point in the worst flooding in the area for at least 70 years.

The deluge of melt water overwhelmed scores of settlements in the Ural Mountains, Siberia and areas of Kazakhstan close to rivers such as the Ural and Tobol, which local officials said had risen by metres in a matter of hours to the highest levels ever recorded.

The Ural River, Europe's third largest which flows through Russia and Kazakhstan into the Caspian, burst through an embankment dam on Friday, flooding the city of Orsk just south of the Ural Mountains.

Downstream, water levels in Orenburg, a city of around 550,000, were rising.

Sirens in Kurgan, a city on the Tobol river, a tributary of the Irtysh, warned people to evacuate immediately. An emergency was also declared in Tyumen, a major oil producing region of Western Siberia - the largest hydrocarbon basin in the world.

"The difficult days are still ahead for the Kurgan and Tyumen regions," Kremlin Spokesman Dmitry Peskov told reporters. "There is a lot of water coming."

— Reuters

Kremlin hints that Putin and Xi will meet again soon

The Kremlin hinted that the Russian foreign minister's current trip to China is a precursor to a forthcoming meeting between President Vladimir Putin and his Chinese counterpart Xi Jinping.

"Of course, we can consider this trip [of Russian Foreign Minister Sergei Lavrov to China] as preparation for upcoming contacts at the highest level. Indeed, such contacts are being planned," Putin's Press Secretary Dmitry Peskov told reporters on Tuesday, according to a Google-translated report from Russian state news agency Tass.

He added it was premature to specify the timing of such a trip.

Russian Foreign Minister Sergei Lavrov is currently on a two-day visit to Beijing, where he has met with his Chinese counterpart, Wang Yi, and the president.

Putin and Xi have met numerous times during their leaderships. During their last run-in in October 2023, Xi said it was the 42nd occasion that the presidents had met since 2013, and that the pair had developed a "strong personal friendship."

— Holly Ellyatt

Ukraine struck Russian aviation factory in Voronezh region, Ukrainian spy source says

Ukraine's military spy agency GUR struck a main production facility of a Russian aviation factory in Russia's Voronezh region, a Ukrainian intelligence source told Reuters.

Russia's defense ministry said earlier on Tuesday that two drones were downed over the region.

The source said the 711th aviation repair plant in the town of Borisoglebsk was hit. It did not provide any details of the scale of the damage.

The town is at least 350 kilometers away from the Ukrainian government-held side of the front line in the northeast. Reuters could not independently verify the accounts.

Kyiv has recently stepped up attacks deep in Russia's territory, targeting military facilities and energy infrastructure that helps Moscow's war effort. It mostly uses various types of long-range domestically produced drones.

— Reuters

Putin under pressure to respond to floods in Russia's south

The Kremlin said Russian President Vladimir Putin is being constantly updated about flooding in the southwest of the country, but has no plans to visit the flood-hit region of Orenburg.

"Floods, of course, remain the focus of attention, including the focus of the president's attention. He continues to receive information regularly," Kremlin spokesperson Dmitry Peskov told reporters Tuesday, RIA Novosti reported.

"The situation remains difficult," he told reporters.

Thousands of homes were flooded in the Orenburg region, as well as in neighboring Kazakhstan, when melting snow caused the Ural river to burst through a dam, flooding the city of Orsk and forcing thousands to flee their homes.

The Kremlin is keen to be seen to be responding to the flooding after residents in Orsk complained that the local authorities were not doing enough to help. On Tuesday, the head of the Russian Ministry of Emergency Situations, Alexander Kurenkov, flew to the region to monitor the situation after being tasked to do so by Putin, Reuters noted.

Peskov said Putin had also discussed the disaster with Kazakh President Kassym-Jomart Tokayev.

— Holly Ellyatt

UK's foreign minister in Washington to bolster Ukraine support

British Foreign Secretary David Cameron will be looking to bolster support for Ukraine when he meets with U.S. officials in Washington on Tuesday.

Amid concerns over war and funding fatigue, as well as the unpredictable outcome of the U.S. presidential election later this year, the U.K.'s Foreign, Commonwealth and Development Office (the FCDO) said such support "remains vital for US and European security."  

On Tuesday, Cameron will meet Republican and Democratic Congressional leaders, as well as U.S. Secretary of State Antony Blinken and other senior U.S. government figures. The foreign secretary is expected to urge U.S. partners to unlock an additional $60 billion in funding for Ukraine that remains blocked by Republicans in Congress.

The U.K. noted that over $184 billion has already been committed to Ukraine by European nations, including over $15 billion from the U.K., in addition to the nearly $74 billion already committed by the U.S. The funding, it said, "is making a huge difference on the battlefields of Ukraine and the waters of the Black Sea. Ukraine has proven time and time again that with the right tools it can succeed."

"Success for Ukraine and failure for Putin are vital for American and European security," Cameron said in a statement.

"This will show that borders matter, that aggression doesn't pay and that countries like Ukraine are free to choose their own future. The alternative would only encourage Putin in further attempts to re-draw European borders by force, and would be heard clearly in Beijing, Tehran and North Korea."

— Holly Ellyatt

Xi Jinping receives Russian foreign minister

Chinese President Xi Jinping has received Russia's Foreign Minister Sergei Lavrov during his visit to Beijing Tuesday.

"We would like to express our highest appreciation and admiration for the successes that you have achieved over the years and, above all, over the last decade under your leadership," Lavrov told Xi, Russian news agency RIA Novosti reported.

"We are sincerely pleased with these successes, since these are the successes of friends, although not everyone in the world shares this attitude, and are trying in every possible way to restrain the development of China. In fact, just like the development of Russia," Lavrov commented.

Earlier Tuesday, Lavrov held talks with his Chinese counterpart Wang Yi. The ministers praised their strategic cooperation and pledged to deepen ties.

— Holly Ellyatt

Ukraine destroys attack drones, missiles launched by Russia

Ukrainian air defense systems destroyed 20 "Shahed" attack drones as well as four missiles from S-300 surface-to-air missile systems, the head of Ukraine's air force said Tuesday.

The drones were shot down over the Mykolaiv, Odesa, Kherson, Dnipropetrovsk, Poltava, Vinnytsia and Lviv regions, Air Force Commander Lieutenant General Mykola Oleschuk said on Telegram. "Shahed" drones are Iranian-made one-way attack UAVs (unmanned aerial vehicles) that have been a prominent feature in the Russia-Ukraine war.

Oleschuk did not mention what happened to the S-300 missiles. CNBC was unable to immediately verify the information in Oleschuk's post.

— Holly Ellyatt

Thousands of people at risk as floods hit Russia's south

Floods are threatening Russia's southern Kurgan region, putting more than 19,000 people's lives at risk, the state news agency said on Tuesday, days after unprecedented flooding displaced thousands of people and inundated a city in the Ural region.

Citing the local branch of Russia's Ministry of Emergency Situations, TASS news agency reported that at least 4,000 homes could also be affected. Emergency measures were put in place in the region, it added.

Some of the worst floods in decades have hit a string of Russian regions in the Ural Mountains and Siberia, alongside parts of neighbouring Kazakhstan in recent days, after Europe's third-longest river burst through a dam.

In the city of Orsk in the Orenburg region, angry residents asked President Vladimir Putin for help, complaining that their local officials had not done enough to help with the worst flooding on record.

The head of the Russian Ministry of Emergency Situations, Alexander Kurenkov, flew to the region on Tuesday to monitor the situation after being tasked to do so by Putin, the ministry said on the Telegram messaging app.

Kurenkov will also visit the Kurgan and Tyumen regions in the Urals, the ministry added.

"Preventive measures are already being taken there, rescue teams have been strengthened, and the forces and means of the Russian Ministry of Emergency Situations have been put on high alert," the ministry said.

The Ural River, which rises in the Ural Mountains and flows into the Caspian Sea, swelled several metres in just hours on Friday due to melt water, bursting through a dam embankment in the city of Orsk, 1,800 km (1,100 miles) east of Moscow.

— Reuters

Russia-China relations have reached an 'unprecedented level,' Lavrov says

Relations between Russia and China have reached an "unprecedented level," Russian Foreign Minister Sergei Lavrov said on Tuesday after holding talks with his Chinese counterpart, Wang Yi.

"We see that thanks to the leaders, Russian-Chinese relations of comprehensive partnership and strategic interaction have reached an unprecedented level, without any exaggeration," Lavrov said, Russian news agencies reported.

"And with the re-election of Vladimir Putin, the continuity of the line for their comprehensive strengthening, of course, received additional guarantees," he said during an official visit to Beijing Tuesday.

Lavrov said cooperation between the nations "exceeds, as our leaders have stated more than once, the military-political alliances of the Cold War, and is not directed against any third party."

Russia and China have become increasingly close in recent years, with Russian President Vladimir Putin and Chinese President Xi Jinping noting that a deep friendship had developed between them.

China is seen as the senior partner in the relationship, however, and is seen as one of the few countries that could wield influence over Moscow when it comes to the war in Ukraine. Nonetheless, China has refused to condemn Russia's 2022 invasion and has done little to bring about peace talks.

— Holly Ellyatt

Russia, Ukraine trade accusations over power plant strikes, Moscow terror attack

The Russian-controlled Zaporizhzhia nuclear power plant on Monday alleged that a Ukrainian drone was shot down over one of its reactors, a day after Russia accused Ukraine of launching three drone attacks on the plant.

Russia has also accused Ukraine without evidence of facilitating last month's terror attack in Moscow that killed 140 people. Terror group ISIS-K claimed responsibility.

Kyiv denies having anything to do with Sunday's strikes or the terror attack, and on Monday Ukraine's state nuclear energy company accused Moscow of orchestrating a "campaign of provocations."

The head of Ukraine's center for countering disinformation, Lieutenant Andriy Kovalenko, said on Monday that Russia's attempts to blame Ukraine for the terror attack were "propaganda."

"At the same time, Russia is striking the ZNPP with drones, pretending that the threat to the plant and nuclear safety is coming from Ukraine," he added.

- Elliot Smith

Russian central bank governor says worker shortage is limiting production

Bank of Russia Governor Elvira Nabiullina told lawmakers in Russia's lower house of parliament that production in the country is being constrained by worker shortages, according to Reuters.

Nabiullina reportedly told the State Duma that Russia's economy is continuing to grow at an impressive rate.

— Elliot Smith

UN sounds alarm after strike on Europe's largest nuclear plant

The United Nations' atomic energy watchdog sounded the alarm Sunday after drones struck a nuclear reactor at the Russian-held Zaporizhzhia nuclear plant in southern Ukraine.

The International Atomic Energy Agency said the serious incident "endangered nuclear safety and security" as Europe's largest nuclear plant was directly targeted by military strikes for the first time since November 2022. However, it added that there are no indications of critical damage at this stage.

"This is a major escalation of the nuclear safety and security dangers facing the Zaporizhzhya Nuclear Power Plant. Such reckless attacks significantly increase the risk of a major nuclear accident and must cease immediately," IAEA Director General Grossi said.

Russian nuclear power company Rosatom said Ukraine's military was behind the attack, without providing any evidence. Ukraine has denied any involvement and alleged Russia launched the drones.

— Elliot Smith

Read CNBC's previous live coverage here:

Zaporizhzhia nuclear plant struck by drones; Zelenskyy calls for more support amid Kharkiv bombardment