London (AP) - British anti-terrorism police said Monday they arrested 12 men in early morning raids on three cities to protect the public amid fears of a holiday season terrorism plot.
Assistant Commissioner John Yates, the U.K.'s lead police officer for counterterrorism, said the suspects were detained in London, in the central English city of Stoke-on-Trent and in Cardiff, Wales.
The arrests follow several weeks of surveillance and are not believed to be linked to other recent plots against Europe or the recent bombing in Sweden.
"The operation is in its early stages so we are unable to go into detail at this time about the suspected offenses," Yates said in a statement. "However, I believe it was necessary at this time to take action in order to ensure public safety."
Police said 11 of the suspects were arrested at or close to their homes at around 5 a.m., while the remaining man was detained at a property in the central England city of Birmingham.
Five of the arrested men are from Cardiff, four from Stoke-on-Trent and three from London, officers said.
Officers said the suspects range in age from 17 to 28 and will be questioned on suspicion of commissioning, preparing or instigating acts of terrorism.
The arrests are the most high profile anti-terror raids in Britain since April 2009, when 12 men were detained in northern cities over an alleged plot to bomb a shopping center in Manchester. Those suspects were later released without charge, though some men were later deported over immigration offenses.
Yates said the latest arrests followed close coordination by officers from several different cities. "This is a large scale, pre-planned and intelligence-led operation involving several forces," he said.