A group of more than 70 MPs cutting across party lines have called on UK Prime Minister Rishi Sunak to seek “immediate release” of a British Sikh imprisoned in India, as he travels to New Delhi to attend the G20 leaders’ summit this week.

In a letter, the MPs urged Sunak to call on Prime Minister Narendra Modi to “immediately release” Jagtar Singh Johal, who has been “arbitrarily detained” for over five years in India, the BBC reported.

Johal from Dumbarton was in Punjab for his wedding when he was arrested in Jalandhar on November 4, 2017, over his alleged role in killings by the Khalistan Liberation Force (KLF), a banned terrorist organisation.

His family says that the 36-year-old has been tortured, including through electric shocks, before being made to sign a blank confession document — allegations that have been denied by the Indian authorities.

He is currently being held at the Tihar Jail and faces a possible death penalty over 10 accusations of murder and conspiracy to murder.

Tory MP David Davis told the BBC that “the first duty of a state should be to prevent a citizen getting harmed”, and that if a citizen had been harmed and subjected to injustice, “the government should be raising the most serious protests”.

“That does not seem to be happening at the moment and that is a failure of the Foreign Office to do its most fundamental duty.”

The UN Working Group on Arbitrary Detention said Johal had been targeted as he was a campaigner for Sikh human rights and wrote “public posts calling for accountability for alleged actions committed against Sikhs by the authorities”.

The MPs’ letter said that the UN Working Group “concluded that Jagtar’s continued detention…lacks any legal basis”.

Brother Gurpreet Singh Johal, who is a lawyer and Labour councillor in Dumbarton, told BBC that given Sunak’s good relationship with Modi, it shouldn’t be a hard ask.

“Almost six years have elapsed, no evidence has been produced against Jagtar. These are just charges alleged against him, and it should be innocent until proven guilty,” Gurpreet said.

The issue has been raised in the past by former Prime Ministers Boris Johnson and Theresa May, with May acknowledging that Johal has been arbitrarily detained, without any prosecution started.

The opposition Labour Party leader Keir Starmer wrote to Sunak early in February asking him what action he intends to take on the matter.

In response, according to The Guardian, Sunak avoided the direct question, saying that the Foreign, Commonwealth and Development Office “continues to provide consular support” to Johal and his family.