It was a grubby, cash-in-a-car conspiracy with worldwide implications: the thwarted assassination of an Indian separatist in New York City.

That plot was outlined on Wednesday by federal prosecutors in Manhattan who charged an Indian nationwide with an try and kill a U.S. citizen who’s a Sikh separatist. The indictment says the plan was devised by an Indian agent, allegations that might complicate the fragile relations between Washington and New Delhi.

The murder-for-hire prices in opposition to the person, Nikhil Gupta, 52, had been announced by the Justice Department days after American officers had expressed concerns to the Indian authorities in regards to the suspected assassination plot in opposition to the separatist.

And the fees got here simply months after Prime Minister Justin Trudeau of Canada accused the Indian authorities of involvement within the June killing of another Sikh separatist, Hardeep Singh Nijjar, in Vancouver, British Columbia. American intelligence businesses provided information to the Canadian authorities about that killing.

The goal in New York was recognized by American officers as Gurpatwant Singh Pannun, who’s common counsel for the New York-based group Sikhs for Justice. Mr. Pannun is an outspoken proponent of independence for the northern Indian state of Punjab, which is residence to a lot of Sikhs, a robust however minority group within the nation.

The indictment stated that the supposed hit man employed to kill Mr. Pannun was the truth is a federal agent.

After the killing in Vancouver, F.B.I. brokers warned a lot of Sikh leaders across the United States about potential threats in opposition to them.

Adrienne Watson, a spokeswoman for the National Security Council, stated Wednesday that after the Biden administration discovered that Mr. Gupta had “credibly indicated” he had conspired with an worker of the Indian authorities, the White House engaged “in direct conversations with the Indian government at the highest levels to express our concern.”

“The government of India was clear with us that they were taking this seriously and would investigate,” Ms. Watson stated in an announcement. “We are providing information to the government of India to aid in their internal investigation. We will continue to expect accountability.”

President Biden directed William J. Burns, the C.I.A. director, to go to India to debate the suspected assassination plot and press the Indian authorities to carry these concerned accountable, in line with U.S. officers aware of the occasions. Mr. Biden himself raised the problem straight with Prime Minister Narendra Modi once they met on the Group of 20 summit in September.

Indian’s Ministry of External Affairs said Wednesday that the United States had “shared some inputs pertaining to nexus between organized criminals, gun runners, terrorists and others” and that the federal government had convened a committee to analyze.

Federal prosecutors in New York stated that the plot concerned a number of accomplices, together with the Indian authorities official, who had a background in regulation enforcement.

That particular person, who was not recognized, is accused of recruiting Mr. Gupta, who prosecutors say then employed a success man to kill Mr. Pannun and offered private details about him, together with his residence handle in New York City and particulars about his day by day actions.

That for-hire killer, nonetheless, turned out to be an “undercover U.S. law enforcement officer,” in line with the U.S. lawyer for the Southern District of New York.

Mr. Gupta was detained by authorities within the Czech Republic in late June, in line with the Southern District. He faces prices of “murder-for-hire and conspiracy to commit murder-for-hire,” prosecutors stated, with every rely carrying a possible sentence of 10 years in jail.

It was not instantly clear Wednesday who was representing Mr. Gupta.

The prices in New York got here after an autumnal diplomatic skirmish between India and Canada, after Mr. Trudeau accused the Indian authorities of involvement within the killing of a Canadian citizen on Canadian soil in June.

The allegation was met with stern denials from Indian authorities.

Mujib Mashal contributed reporting.