The brother of Jagtar Singh Johal, a British Sikh jailed in India, has written to the Home Office to ask why he is being repeatedly stopped at the airport by British border police.

Gurpreet Singh Johal, a Labour councillor in Dumbarton, asked if it was linked to his legal efforts to discover whether British intelligence played a role in his brother’s arrest eight years ago.

He told the Guardian: “I have been repeatedly stopped at the British border, and no explanation is being given. I don’t know if this is an attempt by someone to intimidate me, but I am not going to stop seeking redress for my brother who has been in jail since 2017 without full trial.”

A UK court hearing is due in a few weeks’ time in which Jagtar’s lawyers, including from the legal organisation Reprieve, will seek to discover if he was arrested in India in 2017 after a tipoff by British intelligence. Much of the UK hearing is likely to be held in closed session.

Jagtar has not been found guilty in any Indian court, and a series of delays caused by the Indian prosecutor’s inability to assemble credible witnesses mean he has been detained without full trial.

Charges against him at state level in Punjab were dismissed by the court in March 2025 as no evidence or witnesses were produced. The largely identical federal-level charges being brought by India’s National Investigation Agency remain.

Gurpreet says he has been stopped four times in the last two years when he has returned to the UK from holiday. Neither the Home Office nor Police Scotland have given him explanations that justify him being taken aside in front of his family. He has been stopped at Heathrow in November 2023 and twice at Glasgow airport in April and July 2024 and once in July 2025. Each time he has been told at the e-gates to “seek assistance” that then leads to a set of inquiries.

After years of delay, Gurpreet’s rare legal tort claim against the British intelligence services is due to reach the court on 6 October. The closed proceedings, made necessary by the involvement of the British intelligence services, mean Jagtar’s own lawyers cannot be present, but parts of the first hearing will be open to media and the public.

Jagtar’s legal team is arguing that a member of the British intelligence services appears to be the individual described anonymously in the 2020 annual report by the UK’s Investigatory Powers Commissioner’s Office (IPCO), which sets out how MI5 and MI6 passed information to foreign authorities about a British national who was then detained and tortured.

The report said the case had been raised by the then UK prime minister with Indian authorities. Theresa May is known to have raised Jagtar’s case in 2018 with the Indian prime minister, Narendra Modi, and other circumstantial evidence suggests the case referred to is Jagtar’s.

Jagtar’s British lawyers are asking the government to admit the individual was Jagtar, grant him redress for the harm he has suffered, to recognise its actions were unlawful and publicly apologise for its role in his suffering.

His lawyers claim he was severely tortured after he was arrested in Jalandhar, Punjab, three weeks after his wedding. At the time local media reported a British Sikh had been arrested on the basis of a tipoff from British intelligence. The alleged torture led to a false confession, his lawyers say.

British rules required ministerial consent for intelligence sharing to occur where there was a risk of torture. The foreign secretary at the time, Boris Johnson, and the court would probably hear if he authorised the sharing of the information with the Indian authorities.

A second possible explanation for Gurpreet’s experience is that the British police have generally increased their targeting of British Sikhs, probably in the wake of pressure from the Indian government.

Gurpreet said: “Being stopped this number of times, sometimes for long periods without proper explanation is concerning.

“I am being asked by my children at the airport what I have done wrong and I cannot tell them except I am campaigning to get my brother released from an Indian jail, or that this is straightforward discrimination.

“It will certainly not lead to me dropping the case against the British intelligence services.”

The Home Office has refused an explanation for the stops, citing the Data Protection Act where complying with the right of access to the information on why he is being stopped “would be likely to prejudice the prevention or detection of crime”.

In addition, the Home Office claims the border police have a right to stop individuals in the national interest. Police Scotland referred the issue to the Home Office, and said there had been no request from Police Scotland for him to be stopped.

A UN working group on arbitrary detention has determined that Jagtar’s detention “lacks [a] legal basis” and was based on “discriminatory grounds” owing to his Sikh faith and his “status as a human rights defender”, and that Jagtar was subjected to torture.

Jagtar is accused of being a member of a terrorist group, the Khalistan Liberation Force (KLF), which has carried out attacks in the Punjab region.

The charges against Jagtar state that he travelled to Paris in 2013 and delivered £3,000 to other KLF figures, with the money then used to purchase weapons employed in a series of murders and attacks against Hindu nationalist and other religious leaders in 2016 and 2017.