LONDON- London's police chief said Friday the threat of a terror attack in Britain is growing and warned that the Christmas holidays were an especially dangerous period.
Metropolitan Police Commissioner Sir Ian Blair said al-Qaida represented the gravest threat to Britain since World War II and was of an "unparalleled nature and growing."
"The threat of another terrorist attempt is ever present," he told British Broadcasting Corp. radio. "Christmas is a period when that might happen. We have no specific intelligence to do (with) that."
He said al-Qaida posed a greater threat than the Irish Republican Army's 1970-1997 failed campaign to force Northern Ireland out of the United Kingdom and into the Republic of Ireland, which killed 1,775 people.
The IRA usually did not aim to cause mass atrocities, did not want to die, gave warnings and was "heavily penetrated" by British intelligence agents, Blair said.
"None of those four apply with al Qaida and its affiliates," he said.
"It took 20 years to penetrate the IRA and I have no doubt that the intelligence services will be attempting that now, but it is a more difficult and a much more recent phenomenon," he said.
Home Secretary John Reid said on Dec. 10 that it was highly likely that terrorists would attempt an attack over the holiday period.
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Last month, Dame Eliza Manningham-Buller -- who heads MI5, Britain's domestic spy service -- said authorities were tracking almost 30 terrorist plots involving 1,600 suspects and that her agency had foiled five major plots since the July 2005 transit bomb attacks in London, which killed 52 commuters and the four bombers.