An Indian government official directed a $100,000 plot to assassinate a prominent Sikh separatist leader in New York City after the man advocated for the establishment of a sovereign state for Sikhs, U.S. authorities announced Wednesday as they unsealed charges brought against a man from India who they say was part of the murder plot.

Last spring, U.S. officials became aware of the plot to kill Gurpatwant Singh Pannun, who is considered a terrorist by the Indian government. The U.S. Drug Enforcement Administration stopped the plot when the foreign government employee recruited an international narcotics trafficker to commit the murder, DEA administrator Anne Milgram said.

The government official was only described as “CC-1” in an indictment unsealed in Manhattan federal court that charged Nikhil Gupta, 52, an Indian national who had lived in India, with murder-for-hire and conspiracy to commit murder-for-hire. U.S. Attorney Damian Williams and other federal official announced the charges in a release.

“The defendant conspired from India to assassinate, right here in New York City, a U.S. citizen of Indian origin who has publicly advocated for the establishment of a sovereign state for Sikhs, an ethnoreligious minority group in India," he said in the release.

Czech authorities arrested and detained Gupta on June 30 in the Czech Republic through a bilateral extradition treaty between the U.S. and the Czech Republic, according to the release. It was not immediately clear when he might be brought to the United States.

The plot was directed by an Indian government agency employee who has described himself as a “senior field officer” with responsibilities in “security management” and “intelligence” and also claims to have served in India's Central Reserve Police Force and been trained in “battle craft” and “weapons," the indictment said. Pannun was only identified in court papers as the "Victim.”

The Indian government employee recruited Gupta last May to orchestrate the assassination, the indictment said.

The White House declined to comment directly on the charges against Gupta, but stressed administration officials acted quickly.

“When we were made aware of the fact that the defendant in this case had credibly indicated that he was directed to arrange the murder by an individual who is assessed to be an employee of the Indian Government, we took this information very seriously and engaged in direct conversations with the Indian government at the highest levels to express our concern,” White House National Security Council spokesperson Adrienne Watson said in a statement.

The White House first became aware of the plot in late July, according to a senior administration official.

The official, who spoke on the condition of anonymity to discuss the sensitive exchanges with Indian government, said White House national security adviser Jake Sullivan met with his Indian counterpart, Ravi Sinha, and underscored that India needed to investigate and hold those responsible accountable.

Sullivan also made clear that U.S. needed an assurance that this would not happen again and warned that another episode could permanently damage the trust established between our two countries, the official said.

Biden then asked CIA Director William Burns to contact his counterpart and travel to India to make it clear that the United States would not tolerate such activities and that his administration expected accountability.

Biden also raised the matter directly with Prime Minister Narendra Modi when they met at the Group of 20 Summit in September in New Delhi.

Secretary of State Antony Blinken and Sullivan raised the issue with Minister of External Affairs S. Jaishankar when he visited Washington in September around the time of the annual U.N. General Assembly.

In October, Director of National Intelligence Avril Haines travelled to India to share information with Indian government officials to aid their internal investigation.

The indictment said Gupta contacted an individual he believed to be a criminal associate to help find a hitman to carry out the killing, but the individual happened to be a confidential source working with the DEA. The confidential source then introduced Gupta to a purported hitman, who was actually a DEA agent, the indictment said.

In June, the Indian government employee gave Gupta the home address of Pannun, his phone numbers and details about his daily conduct, including surveillance photographs, which Gupta then passed along to the undercover DEA agent, the indictment said.

It said Gupta directed the undercover agent to carry out the murder as soon as possible, but also warned the agent not to commit the killing around the time of anticipated engagements between high-level U.S. and Indian officials.

India had set up a high-level inquiry after U.S. authorities raised concerns with New Delhi that its government may have had knowledge of a plot to kill a Sikh separatist leader on American soil, an Indian official said on Wednesday.

The U.S. side shared some information and India "takes such inputs seriously since they impinge on our national security interests as well, and relevant departments were already examining the issue,” a statement by External Affairs Ministry spokesman Arindam Bagchi said.

In September, Canadian Prime Minister Justin Trudeau said there were credible allegations that the Indian government may have had links to the assassination in that country of Sikh activist Hardeep Singh Nijjar. India rejected the accusation as absurd, but Canada expelled a top Indian diplomat and India responded with the same measure.

According to the New York indictment unsealed Wednesday, Gupta told the undercover DEA agent the day after Nijjar's murder that Nijjar “was also the target” and “we have so many targets” and he added that in light of Nijjar's murder, there was “now no need to wait” in carrying out the New York assassination.

Two days after Nijjar was killed, the Indian government official behind the New York assassination plot sent Guupta a news article about the New York assassination target and messaged Gupta that “(i)t's (a) priority now,” the indictment said.

Canadian Foreign Minister Mélanie Joly on Wednesday declined to comment on the U.S. indictment but said “we stand by our own credible allegations that there was a killing of a Canadian on Canadian soil linking to Indian agents.” Joly said she’s had numerous conversations U.S. with Secretary of State Blinken about the matter as well as her Indian counterpart.

Pannun has been a leading organizer of the so-called Khalistan referendum, inviting Sikhs worldwide to vote on whether India's Punjab state should become an independent nation based on religion. Organizers of the nonbinding referendum hope to present the results to the U.N. General Assembly in about two years. He is also general counsel with the Sikhs for Justice organization was banned by India in 2019.

Bagchi said that the Indian government formed a high-level inquiry committee on Nov. 18 to look into all the aspects of the matter.