SECURITY bosses let thousands of al Qaida members into the UK during the 1990s, former spy David Shayler has claimed.

The renegade ex-MI5 agent, who was jailed for selling top secret documents to a newspaper, also said some of the terrorists were granted British citizenship in an amazing blunder by his former bosses.

"In the early 1990s MI5 was very slow to get to grips with al Qaida,'' Middlesbrough-born Mr Shayler said in a TV interview.

"Despite repeated warnings they let in thousands of al Qaida members into this country who are all still here - some of whom have gained British citizenship, which makes it very difficult to expel them.''

Mr Shayler revealed his fears on the Tyne Tees programme, The Sunday Interview.

He based his claims on information from French security service officials who, Mr Shayler said, warned their British counterparts that al Qaida terrorists were trying to get into the country.

In 2002, he was jailed for risking British agents' lives by his "blinkered arrogance''.

An Old Bailey jury convicted him of three charges under the Official Secrets Act after selling top secret documents, which were packed with names of agents, to a newspaper for £40,000.

He said he was a whistleblower trying to expose corruption and incompetence in the secret service.

But he remains convinced the UK is under great threat from an attack by Osama bin Laden's feared terror group.

Mr Shayler told the programme: "At one point the French intelligence service mentioned that tens of thousands of al Qaida members came into Britain from France. The French got on top of al Qaida very quickly. In this country we have always had a problem with resources and for that reason our security has been put at risk.

"These people are here now and if they wanted to attack us I am sure they could,'' he said.

"I think they (Home Secretary David Blunkett and Scotland Yard Commissioner Sir John Stevens) have always known there has been a lot of people here. I think we have been given a period of grace and that may change at any time.

"We have already seen attacks in Istanbul on British targets and I think it is only a matter of time before something big happens in this country.''

Mr Shayler's revelations come only days after Osama bin Laden offered to make peace with Europe if soldiers were pulled out of Islamic states.