"No one should ever be tortured"
According to a high court complaint, Jagtar Singh Johal was tortured in India after UK spy agencies passed on information about him.
The British Sikh campaigner was arrested in Punjab two weeks after his wedding in October 2017.
Mr Johal was arrested under the anti-terror laws, being accused of conspiring to murder a number of right-wing Hindu leaders.
Mr Johal, from Dumbarton, Scotland, says he was tortured, including being given electric shocks.
He also faces a possible death sentence.
The campaign group Reprieve, which is representing him, says it has uncovered documents suggesting MI5 and MI6 tipped off the Indian authorities about their client.
In a petition about the case, it said:
“No one should ever be tortured, especially not with the assistance of the UK government.
Mr Johal’s brother, Gurpreet Singh Johal, a solicitor, confirmed that legal action was being taken against the UK government.
He tweeted: “Jagtar, is taking the UK government to court for his unlawful detention and torture in India.
“If this can happen to my brother, it could happen to any Brit travelling overseas.”
In August 2022, Jagtar Singh Johal’s lawyers lodged a claim in the high court against the Foreign Office, the Home Office and the attorney general.
It alleges that UK intelligence agencies unlawfully shared information with the Indian authorities when there was a risk of torture.
Reprieve said: “As foreign secretary and potential future prime minister, Liz Truss has a duty to right the wrongs of foreign secretaries before her and, in good faith, to bring Jagtar home and reunite him with his family; ban intelligence sharing where there is a real risk of torture or the death penalty; [and] give torture survivors a right to know if the UK was involved in their abuse.
“Our government should protect us, not expose us to torture and the death penalty.”
In 2022, Boris Johnson acknowledged that the Indian authorities had arbitrarily detained Johal, adding that the UK government had consistently raised concerns about his treatment and right to a fair trial.
Jagtar Singh Johal spent four and a half years in detention before being formally charged with conspiracy to commit murder and being a member of a terrorist gang.
Mr Johal denies any wrongdoing.
The Foreign Office said it would not comment on an ongoing legal case.