Extreme action will be taken if allegations that a British man arrested in India has been tortured by police are true, a Cumbrian MP has suggested.

Rory Stewart, also a Foreign Office minister, told MPs that the Government was working closely to investigate the case of Jagtar Singh Johal, from Dumbarton in West Dunbartonshire, who was detained in Jalandhar in the state of Punjab on November 4.

Campaigners say Mr Johal, 30, has been tortured by police and Mr Stewart said the Government would "take extreme action if a British citizen is being tortured".

During Foreign Office questions in the Commons, the SNP's Martin Docherty-Hughes (West Dunbartonshire) raised his constituent's case, and asked Foreign Secretary Boris Johnson what discussions he had with the Indian Government about their human rights record in Punjab.

"Critically in relation to my constituent Jagtar Singh Johal who has been in custody since November 4 without charge and now with the possibility or the accusation of torture, the Prime Minister yesterday on BBC radio indicated their personal interest.

"Can the Secretary of State advise me and the House how he's working with the office of the Prime Minister to assist my constituent and his family in Dunbarton?"

Mr Stewart said the case was being taken very seriously.

He told MPs: "The Deputy High Commission managed to gain access - we have now had a meeting with the constituent.

"We take any allegation of torture very seriously, as indeed would the Indian government. It is completely unconstitutional - it is offensive to the British Government - and we will work very closely to investigate and of course will take extreme action if a British citizen is being tortured."

The Sikh Federation UK says no official charges have been brought against Mr Johal, but local media reported that his arrest was linked to the killing of Hindu leaders in Punjab.

The organisation said Mr Johal moved to judicial custody after appearing in court in Punjab earlier this month, sparking hopes the "physical torture" will come to an end, but he was later returned to police custody without charge.