Tariq al-Karbouli, the alleged leader of the cell, was picked up Monday in the Abu Ghraib area west of Baghdad, Iraqi officials said. The other members of the cell were apprehended in a series of raids that ended on early Tuesday, the officials added.

Two bomb-laden trucks exploded last Thursday at police stations in Fallujah, 40 miles west of Baghdad, killing 17 people and leveling buildings, police reported.

The brazen attacks in the most heavily guarded city in Iraq raised questions about the ability of Iraqi security forces to ensure security as the US scales down its combat role under the newly ratified US-Iraqi pact, which calls for an American pullout within three years.

Fallujah is located in Anbar province, the mostly Sunni area of western Iraq that had been the main theater of the war until Sunni tribes there broke with al-Qaida last year and joined forces with the Americans.