LONDON, Aug 3 (AFP) - Thirteen men were arrested Tuesday under Britain's main anti-terrorist law in an ongoing operation in London and other parts of England, the Metropolitan Police said.
"Thirteen men were arrested under the Terrorism Act 2000 this afternoon and evening as part of a pre-planned, on-going intelligence-led operation," the police said in a statement.
"The men have been arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism," it said without elaboration.
It was unknown whether the arrests were in any way connected with a heightened state of alert in the United States.
"The arrests were made in northwest London, Hertfordshire, Bedfordshire and Lancashire," the police statement said, referring to counties in central and northwest England.
"Officers are executing a number of search warrants at residential premises ... in London, Hertfordshire, Bedfordshire and Lancashire ... granted under the Terrorism Act 2000," it added.
"Searches are ongoing and are expected to take some time to complete."
The suspects were all in their 20s and 30s, the police said, adding that they were taken to a central London police station to be questioned by officers of the Metropolitan Police's anti-terrorist branch.
"Todays operation is part of continuing and extensive inquiries by police and the Security Service into alleged international terrorism," the police statement said.
On Sunday the Home Office said Britain remains under a "real and serious" threat from terrorism, after the US authorities warned of potential truck or car bomb attacks against financial institutions in Washington and New York.