An Indian government official directed an unsuccessful plot to assassinate a Sikh separatist on U.S. soil, the U.S. Justice Department said on Wednesday, in announcing charges against a man accused of orchestrating the attempted murder.

Federal prosecutors in Manhattan said Nikhil Gupta, 52, worked with the Indian government employee, whose responsibilities included security and intelligence, on the plot to assassinate a New York City resident who advocated for a Sikh sovereign state in northern India.

Prosecutors did not name the Indian official or the target. Gupta was arrested by Czech authorities in June and is awaiting extradition. He could not be reached for comment.

"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," Damian Williams, the top federal prosecutor in Manhattan, said in a statement.

The charges come after a senior Biden administration official last week said U.S. authorities had thwarted a plot to kill a Sikh separatist in the United States and issued a warning to India over concerns the government in New Delhi was involved.

That official said Gurpatwant Singh Pannun, who says he is a dual citizen of the United States and Canada, was the target of the foiled plot.

The issue is highly delicate for both India and the Biden administration as they try to build closer ties in the face of an ascendant China perceived as a threat for both democracies.

India's Washington embassy and its foreign ministry did not immediately respond to requests for comment, but earlier on Wednesday India's foreign ministry said New Delhi would formally investigate the concerns aired by the United States.

"India takes such inputs seriously since they impinge on our national security interests as well," the ministry said, vowing to "take necessary follow-up action" on the findings of the panel set up on Nov. 18.

The U.S. started voicing its concerns and related details to Prime Minister Narendra Modi's government as early as April, an Indian official who is aware of the matter, but not authorized to speak to the media, told Reuters.

The official said the issue was also discussed on Nov. 10, when U.S. Secretary of State Antony Blinken and Defense Secretary Lloyd Austin met their counterparts in the Indian capital for the so-called 2+2 dialogue.

Prosecutors did not name the target of Gupta's alleged plot, who they described as a vocal critic of the Indian government who leads a U.S.-based organization that advocates for the secession of India's Punjab state, which is home to a large population of Sikhs.

News of the incident comes two months after Canada said there were "credible" allegations linking Indian agents to the June murder of a Sikh separatist leader, Hardeep Singh Nijjar, in a Vancouver suburb, something India has rejected.

According to prosecutors, the official recruited Gupta in May 2023 to orchestrate the assassination. Gupta had previously told the official he had been involved with trafficking drugs and weapons, prosecutors said.

Gupta then reached out to someone he believed was a criminal associate for help hiring a hitman, but that associate was actually a Drug Enforcement Administration undercover agent, prosecutors said.

The day after Nijjar was killed, Gupta wrote the undercover DEA agent saying Nijjar "was also the target" and "we have so many targets," prosecutors said.

Gupta faces two counts of murder-for-hire and murder-for-hire conspiracy. He faces a maximum sentence of 20 years if convicted.

The Indian government has complained about the presence of Sikh separatist groups outside India, including in Canada and the United States. The groups have kept alive the movement for Khalistan, or the demand for an independent Sikh state to be carved out of India.

The movement is considered a security threat by India. Sikh militants were blamed for the 1985 bombing of an Air India Boeing 747 flying from Canada to India in which all 329 people on board were killed.

The cause hardly has any support in India presently and was crushed within the country by the government in the 1990s.