A gang of suspected Algerian terrorists with alleged links to Al Qaeda are on the run in Britain after breaching immigration checks.
One of them has already been caught working for a Heathrow freight firm, media reports said on Sunday.
The Heathrow worker, now in prison, was one of more than a dozen suspected terrorists allowed to enter Britain, The Sunday Times said in an article.
According to the report, senior anti-terrorist officers are furious that Al Qaeda suspects breached immigration checks and that one of them was able to penetrate the world's biggest international airport.
The suspect was arrested recently as he was about to board an international flight. Anti-terrorist officers discovered he was living near the airport and working for an air services company after the Bank of England circulated a list of 17 Al Qaeda suspects whose assets were to be traced and frozen.
The 17 names were passed to banking authorities by Italian intelligence last October after they arrested several leading Al Qaeda suspects, the report said.
The three men -- who had allegedly been in contact with the Italian Al Qaeda cell -- were discovered in Britain in January but the arrests have not been publicised.
Two of them are being held at Belmarsh high security prison in southeast London under the Terrorism Act 2000.
One of those detained is alleged to be one of Al Qaeda's European leaders, while the third man has been convicted in absentia of committing terrorist offences in Algeria. He is believed to be a senior figure in Takfir wal-Hijra, now part of Al Qaeda.
The third man is believed to be living in London's Algerian community, and has been seen at the Finsbury Park Mosque. He was able to claim asylum in Britain despite being named on a European Union list of terrorist suspects sent to police forces and immigration authorities.
The report quoted a senior immigration officer describing the service and asylum system as a 'mess'.