The prime minister has confirmed that he raised the case of a Scottish Sikh who has been held by Indian authorities since 2017, in talks with the country's prime minister.
Rishi Sunak had faced pressure to highlight the case of Jagtar Singh Johal, from Dumbarton, whose family claim has been the victim of torture.
More than 70 MPs demanded that Mr Sunak lobby for his release.
Earlier this week, the Foreign Office ruled out intervening in the case.
However, after speaking to his Indian counterpart Narendra Modi, Mr Sunak confirmed he raised the case along with other consular issues.
He did not provide details, but said: "The foreign office are continuing to provide support to Mr Johal's family and will continue to do so".
Mr Johal, a 36 year-old campaigner for Sikh human rights, travelled to India in October 2017 to get married.
He was shopping with his wife when his family say he was snatched from the street by plain-clothes officers of the Punjab Police and forced into an unmarked car.
He says he was beaten and tortured by officers over the following days, and given electric shocks to his genitals, before being made to sign a blank confession document.
These allegations have been denied by the Indian authorities.
Mr Johal has remained in detention in a series of Indian prisons ever since, accused of funding the purchase of weapons used to assassinate a number of right-wing Hindu religious and political leaders in the Punjab.
'Talk is meaningless'
He is currently facing eight charges of conspiracy to murder, linked to political violence in India, and could receive the death penalty.
He denies the charges against him and says his arrest and trial are political.
The UK government has previously refused to call for Mr Johal's immediate release - saying it could be seen as interference in the judicial process and would not be in his best interests.
On the plane to Delhi, when asked if he would be raising the case, Mr Sunak had said: "I'll be raising a range of things with Prime Minister Modi - this is something that, just so people are reassured, has already been raised on multiple levels on multiple occasions."
On Friday, Mr Johal's brother Gurpreet - a lawyer and Labour councillor - accused Mr Sunak of allowing Mr Johal to "rot in jail."
After hearing about Mr Sunak's involvement he said: "I am pleased that the prime minister has raised my brother's case with his counterpart, but raising is not enough unless he has called for Jagtar's release in line with the UN Working Group on Arbitrary Detention's findings.
"Clearly, the prime minister had no option other than to raise Jagtar's case, after so many MPs demanded he do so.
"I fear that this is just more talk from the UK government and no action. The campaign continues until Jagtar is back home in Scotland."
'Lack of leadership'
Human rights group Reprieve's director Maya Foa said: "Theresa May 'raised' Jagtar's case. So did Boris Johnson. But six years after his abduction and torture he's still in prison, facing a possible death sentence for something he didn't do.
"The government often says ministers have raised the case a hundred times, as if that makes their failure to seek the release of an arbitrarily detained British national any less shameful.
"What did Rishi Sunak say to Narendra Modi about the case and how did he respond? Without answers to these questions, the prime minister's talk is meaningless."
Dabinderjit Singh, the principal adviser to the Sikh Federation, said Mr Sunak had appeared "very reluctant" to press the Scot's case since entering No 10 almost a year ago until being "forced through pressure" from MPs to do so.
He added: "He has, however, demonstrated his weakness and lack of leadership by shamefully falling to stand up for the rights of a British citizen and calling for Jagtar's immediate release.
"Rishi Sunak and his Foreign Office ministers are now talking utter nonsense in terms of Jagtar's best interests and justice.
"They appear scared and clueless on how best to apply diplomatic pressure on India and are leaving it to the corrupt Indian judicial system."