Jagtar Singh Johal, 33, was arrested on November 4, 2017 after travelling to the Punjab for his wedding.
Local media has linked his detention to the killing of Hindu leaders in Punjab.
Human rights group Reprieve has written to to Foreign Secretary Dominic Raab over concerns that some of the Dumbarton man’s charges carry the death penalty, The Times and the BBC have reported.
“Reprieve is concerned that the risk of Jagtar being sentenced to death and executed is high given the politicised nature of this case,” the Times quoted Reprieve’s statement as saying.
Mr Singh Johal said he had signed a blank confession after being tortured.
“They made me sign blank pieces of paper and asked me to say certain lines in front of a camera under fear of extreme torture,” he said via his lawyer.
He also repeated allegations of torture and mistreatment by Indian authorities.
Martin Docherty-Hughes MP has previously raised the case in the House of Commons and arranged for Mr Raab’s predecessor Jeremy Hunt to meet with his constituent’s family.
“Irrespective of what Jagtar’s been accused of, he is a British Citizen and the Foreign Office has an obligation to ensure his rights under international law are protected,” the West Dunbartonshire MP said in March 2019.
The Foreign and Commonwealth Office has been contacted for comment.
