British police Wednesday arrested 12 people in a counterterrorism operation, and locations were being searched, authorities said.
Arrests were carried out in a series of raids in northwest England, police said. Participating agencies included Merseyside Police, Greater Manchester Police and the Lancashire Constabulary, according to a statement from Greater Manchester Police.
The statement said police would not divulge or confirm any of the addresses being searched.
"As the operation is still ongoing and is at an early stage, we would appreciate media understanding and cooperation," it said.
Merseyside police issued a similar statement.
"Today's action is part of an ongoing investigation and we have acted on intelligence received," said Steve Ashley, chief superintendent of Merseyside police.
"We understand that this kind of police activity can cause concerns to people living in nearby communities. The extra patrols, cordons and measures we have in place have been implemented to make sure we are doing everything we can to reassure the public and maintain public safety."
Home Secretary Jacqui Smith, in a written statement, congratulated police for the "successful anti-terrorism operation which has resulted in 12 arrests at a number of locations."
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