US prosecutors have charged an Indian man for his alleged involvement in a foiled plot to kill a Sikh leader in New York.

Federal prosecutors in the Southern District of New York announced the man's indictment on Wednesday.

The indictment says an Indian government official recruited the man in around May this year to orchestrate the assassination of the Sikh leader.

The man contacted a purported hitman, who was in fact an undercover officer of the US Drug Enforcement Administration.

The court documents say the targeted leader heads a US-based organization that advocates the secession of a state in northern India that is home to a large population of Sikhs. The Indian government is said to have been watching him closely.

White House National Security Council spokesperson Adrienne Watson said in a statement, "When we were made aware of the fact that the defendant ... 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."

She added, "We will continue to expect accountability from the Government of India based on the results of their investigations."

A Sikh leader in Canada was murdered in June this year.

The Canadian government pointed to the involvement of the Indian government, which has soured relations between the two countries.