By Jon Silverman BBC home affairs correspondent

The Foreign Office is being urged to investigate allegations that a British businessman arrested in Thailand on drugs charges was asked to pay a bribe to a local judge.

Kevin Quill, 40, was sentenced to six years in prison in May, after the police found 100 amphetamine tablets when they searched his car.

Mr Quill, who runs a hotel and three bars in the tourist resort of Pattaya, maintains his innocence and says that he was set up by associates anxious to take control of his businesses.

Alice Mahon, the MP for Halifax - where Mr Quill's mother lives - has taken up his case and is seeking an urgent meeting with the Foreign Office minister, Baroness Amos.

"My gut feeling is that he's been stitched up," said Mrs Mahon, " and I think it's highly possible that he was asked to pay a bribe for his freedom. "

Mr Quill was arrested in October 2000 when the police found drugs among a consignment of cigarettes in his car.

"Secret" informant

According to Mr Quill's sister, Lorraine Hawksworth-Quill, the officers opened only two of the cartons and found 100 amphetamine tablets with a local street value of around �60.

"We have a police video of the search and arrest," said Mrs Hawksworth-Quill, "and it seems pretty clear that they knew what they were expecting to find right from the start. After all, why did they not open any of the other cartons?"

The police have said they were acting on a tip-off from a "secret " informant.

We know some police have acted corruptly for many years in Thailand

Stephen Jakobi, Director, Fair Trials Abroad

But Kevin Quill suspects close associates who knew the timing of his journey to the airport, and who, he says, had an ulterior motive for wanting him out of the way.

Mr Quill was jailed for six years in May 2002 but is free on bail pending an appeal. According to his sister, the bribe was proposed a fortnight ago.

"Kevin says he was visited by a police officer who told him that if he paid about �16,000, the judge hearing his appeal would quash the conviction. Kevin told him he must be joking and is determined to fight on to clear his name. "

Police corruption

Though there is no written evidence to support the allegation of corruption, documents support Mr Quill's contention that he is innocent of any crime and has been set-up.

A letter written by the British consul in Bangkok, Deryck Fisher, says that a senior police officer from an elite anti-corruption unit "having reviewed the evidence, believes that Kevin Quill had been framed and that there was no substance to the allegations against him. He offered an apology on behalf of the police."

The director of Fair Trials Abroad, Stephen Jakobi, said the case illustrated many of the problems foreigners encountered with the Thai judicial system.

" We know some police have acted corruptly for many years in Thailand," said Mr Jakobi, "and it would be extremely surprising if judges were immune from this infection."

No-one at the Thai embassy in London was available for comment.