Prime Minister Gordon Brown has stepped up pressure on American forces for the release of a detained businessman.

Mr Brown’s intervention comes as Kadhum Al-Sarraj, 29, of Carshalton, prepares to spend his tenth month in Baghdad’s Camp Cropper after he was arrested when a heart monitor he created was mistaken for a bomb.

In early April an Iraqi court dismissed the charges against him but US authorities have given no indication when he will be freed.

In a letter to Carshalton and Wallington MP Tom Brake, Mr Brown said: “Officials at the British Embassy in Baghdad have previously made it clear to the US authorities that we have an interest in Mr Al-Sarraj and wish his case to be resolved as quickly as possible.

“While there are limitations on what we can do given that Mr Al-Sarraj is not a British national, I have asked that the British Embassy in Baghdad approach the US again to remind them of our continued interest in Mr Al-Sarraj and to ask for an indication of when he will be released.

“I have also asked that the Foreign and Commonwealth Office continue to keep you informed.”

Earlier this month Mr Al Sarraj’s wife Shereen Nasser, 24, a research assistant, attended a meeting with the Iraqi charge d’affaires, at the Iraqi embassy in South Kensington, accompanied by her local MP Tom Brake, who described it as “constructive”.

However, Mrs Nasser said she remained concerned that her husband could be detained for years to come.

Mr Brake said he welcomed the Prime Minister’s letter.

He said: “The Prime Minister’s support is a huge boost to Shereen’s campaign.

“I hope the PM’s intervention will lead to a speedy and successful outcome.”

A spokesman for the American Embassy in Baghdad said: “The Iraqi legal system has ruled that he has not violated Iraqi laws. In accordance with the January 1 security agreement, he will be processed for release in the order that his threat classification dictates.

“We are making every effort to be as transparent and fair in our operations as possible.”