London:
In the latest of several European terrorism alerts, the British police arrested 12 men before dawn on Monday in raids in three cities under counter-terrorism laws - the biggest operation of its kind for months.
The action, designed "to ensure public safety," as the police put it, followed a suicide bombing in Sweden earlier this month and alarms in Germany over the reported threat of a terror attack modeled on the onslaught by gunmen in Mumbai.
But a Scotland Yard spokesman, speaking in return for anonymity under police rules, said the arrests were not linked to an unfolding terrorism investigation in Luton, just north of London, where Taimour Abdulwahab al-Abdaly, a 28-year-old Swedish-Iraqi man who killed himself and wounded two others when he detonated two bombs in Stockholm on December 11, is said to have lived and studied. The spokesman said that no arrests have been made in Mr. Abdaly's case, and that the enquiry continues.
The BBC said the 12 men arrested on Monday were involved in a plot to bomb unspecified targets in Britain, inspired by Al-Qaida. Some of the suspects were said to have Bangladeshi origins. John Yates, Britain's ranking counter-terrorism police officer, said the detained men were from London, the Welsh city of Cardiff and Stoke-on-Trent in the English Midlands.
"The operation is in its early stages so we are unable to go into detail at this time about the suspected offenses," Mr. Yates said in a statement. "However, I believe it was necessary at this time to take action in order to ensure public safety."
He described the raids as a "large scale, pre-planned and intelligence-led operation" involving several police forces. The officers who made the arrests - apparently after weeks of surveillance - were not armed, the police said, suggesting that they had not moved to thwart an imminent terror attack.
A police statement said 11 of the men, aged between 17 and 28, were arrested "at or near their home addresses" but one of the detainees from Stoke-on Trent was seized "at a domestic property in Birmingham."
"Searches are now being conducted at the home addresses, plus the address in Birmingham and another residence in London," the statement said.
The group was made up of five men in Cardiff, four living in Stoke-on-Trent and three from London. The police said they would be questioned "on suspicion of the commission, preparation or instigation of an act of terrorism" in Britain.
The arrests appeared to be the biggest since April 2009, when police arrested 12 across northern England and then released them without charge, saying an Al-Qaida bomb attack had been averted in the northwestern city of Manchester.
European officials have insisted that there are no specific threats of attacks timed to coincide with the holiday season, despite some reports that the December 11 bombing in Stockholm was part of an Al-Qaida conspiracy to strike at that period.
The latest alarm came less than three months after the State Department in Washington cautioned American citizens in Europe about reports of a planned attack on a European city.
Britain has been a focus of terrorism since four suicide bombers killed 52 people in attacks on the London rapid transit system on July 7, 2005. Currently, the official terrorism threat level stands at "severe," the second highest, meaning that a terrorist attack is highly likely.
A British intelligence operative, who spoke in return for anonymity under departmental rules, said that the investigation into the 12 men arrested on Monday had drawn on cooperation between several intelligence agencies and electronic monitoring in several European countries.
Internet communications, he said, had been intercepted, but he declined to give details.
A British former counter-terrorism official, who did not want to be identified by name while discussing current operations, said in an interview last month that Scotland Yard is currently working on almost a hundred terror cases. Thirty of those, he said, are pressing, with around 10 classified as urgent or imminent.