The allegations echo a similar claim made by Canada over the June killing of a different Sikh separatist leader near Vancouver which led to a major diplomatic flareup between Ottawa and New Delhi.
According to the Justice Department, Indian national Nikhil Gupta was arrested on June 30 -- just over a week after Indian Prime Minister Narendra Modi's state visit to Washington.
Gupta, 52, has been charged "in connection with his participation in a foiled plot to assassinate a US citizen" of Indian origin in New York, the Justice Department said.
The statement further described his target as "a vocal critic of the Indian government" who "leads a US-based organization that advocates for the secession of Punjab," a northern Indian state with a large population of Sikhs.
The Financial Times, which reported the alleged assassination plot last week, identified Gupta's target as US-Canadian citizen Gurpatwant Singh Pannun.
He is a leader of Sikhs for Justice, a US-based group that is part of a movement calling for an independent Sikh state called Khalistan.
After the Financial Times report, the White House said last week it was treating the alleged plot with "utmost seriousness" and had raised the issue with the Indian government.
The Justice Department further alleged on Wednesday that an unidentified "Indian government agency employee who has variously described himself as a 'Senior Field Officer' with responsibilities in 'Security Management' and 'Intelligence'" hired Gupta to orchestrate the killing.
Gupta, who lives in India, was arrested by authorities in the Czech Republic under US extradition orders.
Canada-India row
Pannun's organization is banned in India, and he is designated as a "terrorist" by New Delhi.
The Justice Department said Gupta had been recruited into the assassination effort in May 2023 and that his June 30 arrest came after he sought to hire a hitman who was actually an undercover US agent.
The unnamed Indian government employee "agreed in dealings brokered by Gupta" to pay the undercover agent $100,000 for the killing, according to US authorities.
Canadian Prime Minister Justin Trudeau in September linked New Delhi to the killing of Canadian citizen Hardeep Singh Nijjar, also a Sikh separatist, on June 18.
The allegations sparked a fierce diplomatic row in the following weeks, with dozens of Canadian diplomats leaving India and New Delhi temporarily suspending visa issuances to Canadians.
Nijjar was also wanted by Indian authorities for alleged terrorism offenses and conspiracy to commit murder, which he had denied to Canadian media.
The Justice Department said that after Nijjar's killing, Gupta told undercover US agents that there was "now no need to wait" on killing the New York City target.
In addition, Gupta allegedly said that Nijjar "was also the target," and that they were just two of "many targets."
Gupta had earlier that month cautioned the hitman not to commit the murder around the time of "scheduled to occur in the ensuing weeks between high-level US and Indian government officials," the Justice Department said.
Modi was hosted by President Joe Biden for a state visit at the White House on June 22.
An Indian government spokesman on Wednesday said that the United States has "shared some inputs pertaining to nexus between organized criminals, gun runners, terrorists and others."
"We had also indicated that India takes such inputs seriously since they impinge on our national security interests," the statement said, adding that a "high-level Enquiry Committee" was established on November 18 "to look into all the relevant aspects of the matter."
