Up to 4,000 British Muslims were trained at al-Qa'ida terror camps

No less than 4,000 Britons have received training at al-Qa'ida camps in the past 10 years, security sources say.

Far greater numbers of British Muslims volunteered to fight for Osama bin Laden's organisation and the Taliban regime in Afghanistan than was previously known, and the vast majority of them are back in this country.

Britain's close alliance with the US in the "war on terror" and the deployment of troops in Afghanistan means it is a prime target for terrorists and attacks are inevitable, Western intelligence officials say.

Sir Stephen Lander, the MI5 director general, said last week: "Anyone who believes terrorist plots can always be foiled is living in Cloud-cuckoo-land. In terms of getting information others want to keep secret, 100 per cent success is never achieved." The security sources say the threat of a large-scale attack in Britain was shown by the recent 20-year prison sentence imposed on Moinal Abedin, a 27-year-old of Bangladeshi origin who was caught making a bomb in Birmingham.

Many of those returning from Afghanistan have been traced, but others have disappeared. The security sources stress that most of the former volunteers are not seen as threats. But some are believed to have retained their terrorist loyalties. The recruitment of Muslims happened at mosques around the country, the sources said. The training took place mainly at camps in Afghanistan, and many of the British Muslims fought in the Taliban ranks against the Northern Alliance. Other recruits are believed also to have seen action in Bosnia and Chechnya.

An al-Qa'ida network stretching across Europe had arranged for the Islamist volunteers to travel to the terrorist camps and then return back home. Others in the recruiting chain include a London based Muslim cleric of Caribbean origin currently facing serious criminal charges; Abu Doha, an Algerian based in Britain, who is fighting extradition to the US to face charges that he plotted to bomb Los Angeles airport; Abu Qatada, who came to Britain from Jordan in 1993 and has been named by the German authorities as a terrorist suspect; and Hassan Butt, a 22-year-old student from Wolverhampton, living in Pakistan, claimed to have sent 200 young Britons to Afghanistan.

Among those believed to have recruited volunteers are Abu Zubair al-Haili, and Mohammed Haydar Zammar. Mr Zubair, who was known by his nickname of "the Bear", is currently under arrest in Morocco. Mr Zammar, who is said to have admitted that he recruited Mohamed Atta, one of the 11 September hijackers, is being interrogated in Syria.