Ms Barton said she was with her fiance at the time of the bombings

James Lee, from Dinas Powys, south Wales, is one of six Britons convicted for the bombings - which killed one Briton and injured others - in November 2000.

His fiancee Gillian Barton said he could not have been involved, and criticised the British Government for not doing enough to help the men.

But the Foreign Office said it remains "deeply concerned" about the case and claimed that most of the men's families have agreed it is not in their best interests to raise its profile.

Ms Barton, who has just moved to Manchester from Riyadh, said she was with her husband-to-be James Lee when the three bombings took place.

She said she could not believe it when she saw the men confessing to the crimes on television - these confessions have since been withdrawn.

"I knew they couldn't have done it - I definitely knew Mr Cottle and James Lee couldn't have done it - I was with them at the time," she said.

Lee appeared on Saudi television confessing to the attacks

She said the British government could have been more forceful in pressing for their release, but admitted it is only the Saudi authorities who can release the prisoners.

"The Saudis know exactly when they are going to release these men.

"I am hoping the royal family will show clemency and allow them to go."

Lee was arrested while working at a hospital in the Saudi capital Riyadh two years ago.

The six men have been accused by the Saudi authorities of conducting a bombing campaign as part of a row between alcohol bootlegging gangs.

The men are hoping to receive clemency after a petition was handed to the Saudi King Fahd.

One Briton was killed in the bombings

Since their arrests, bombings have continued to plague the city - including one attack in May which killed two Britons.

Earlier this year, the government defended its handling of the case of two UK men jailed in Saudi Arabia after being criticised for not using "plain speaking".

On Friday, John Pugh - MP for Southport - demanded the government should ask whether its current tactics were working in the case.

Les Walker, from Neston, Merseyside, and James Cottle, of Urmston, Greater Manchester, were jailed in 2002 for allegedly planting car bombs in the Saudi capital Riyadh.

The other imprisoned Britons are Sandy Mitchell and William Sampson, both from Glasgow, and Peter Brandon from Cardiff.