The US says it foiled an alleged plot to assassinate an American citizen in New York who advocated for a Sikh separatist state.

Nikhil Gupta, an Indian national, was charged on Wednesday. He was directed by an Indian government employee, according to the indictment.

He has been charged with murder-for-hire over the plot, which prosecutors said was orchestrated from India.

The alleged target was not named in the court documents.