Indian national Nikhil Gupta, accused of being involved in a murder-for-hire plot against a Sikh extremist on American soil, on Monday pleaded not guilty in the case at a federal court here.

Gupta, 52, was extradited to the US from the Czech Republic on Friday.

He was arrested in the Czech Republic last year at the request of the US government on charges of being involved in a plot to assassinate Khalistani separatist Gurpatwant Singh Pannun in New York. Pannun holds dual American and Canadian citizenship.

Gupta was produced before a federal court in New York on Monday, where he pleaded not guilty, according to his attorney, Jeffrey Chabrowe.

The Czech Constitutional Court last month rejected a petition by Gupta against his extradition to the US to face the charges.

US federal prosecutors allege that Gupta had been working according to the directions of an unnamed Indian government official.

India has, however, denied its involvement in such a case and has instituted a high-level investigation into the allegations.

“This is a complex matter for both our countries," Gupta's attorney Chabrowe told PTI ahead of his client’s arraignment in a federal court here.

"It is extremely important that we refrain from rushing to conclusions so early in the process. Background and details will develop that may cast government allegations into an entirely new light," Chabrowe said.

"We will pursue his defence vigorously and ensure he receives full due process, regardless of outside pressures,” he added.

Earlier, the Czech Justice Minister confirmed that Gupta has been extradited to the US.

"On the basis of my decision on (June 3), Indian citizen Nikhil Gupta, who is suspected of conspiracy to commit murder-for-hire with intent to cause death, was extradited to the US on Friday (June 14) for criminal prosecution," Czech Justice Minister Pavel Blazek said in a post on X.

Federal prosecutors allege that Gupta hired a hitman to kill Pannun and paid USD 15,000 in advance.

Gupta, through his attorney, has denied the charges and said that he has been "unfairly charged".

The Washington Post in April 2024 reported that Vikram Yadav, a Research and Analysis Wing (R&AW) officer, was the Indian official behind the plot. The paper also said the then R&AW chief Samant Goel sanctioned the operation.

India's Ministry of External Affairs, however, dismissed the report, saying it makes “unwarranted and unsubstantiated imputations” to claim that Indian agents were involved in the plot to kill Pannun.

India has publicly said a high-level inquiry is looking into the evidence shared by the US in the alleged plot to kill Pannun.