Iraqi special forces backed by coalition troops raided a government intelligence headquarters on Sunday and uncovered evidence of torture and links to bomb attacks, the British military said.
Troops stormed the local headquarters of Iraqi interior ministry's domestic intelligence agency in the southern port city of Basra, and released more than 37 prisoners being held there, Iraqi police told AFP.
"In the early hours of this morning there was a search and detention operation by the Iraqi counter-terrorist force supported by multinational forces," said British spokesman Major David Gell.
"Five individuals were arrested on suspicion of serious terrorist activity, including involvement with roadside bombs and attacks against both civilians and multinational forces," he added.
"The Iraqi national intelligence building was subsequently struck and further evidence of significant criminal activity, such as torture, was found."
Following the raid, Iraqi intelligence agents wearing black balaclava masks and carrying Kalashnikov assault rifles showed reporters around their building, including the cell were prisoners had formerly been kept.
British forces based in southern
Iraq have been confronted with serious corruption among Iraqi security units, many of which are inflitrated by or controlled by violent Shiite political factions and militia groups.
It was not clear whether the coalition troops that accompanied the raid were Americans -- as claimed by Iraqi police -- or British, as would normally be the case in Basra, where their Iraq force is based.