The association, an influential group of Sunni scholars who hold sway over many Sunnis, especially in Anbar province, complained that the troops detained five of its people.

An association official who demanded anonymity told Reuters that member of the U.S. army attacked Umm al-Qora mosque complex in the Iraqi capital at around 3 a.m. on Sunday, blowing doors off hinges and ransacking offices.

"They took Sheikh Unis al-Ugaidi (a member of the association), two employees and two guards," said a source in the office of Sheikh Harith al-Dhari, the head of the association.

"We do not know the reason, but it's obvious, it's due to the Association's attitude toward the occupation," he said. TV footage showed "spent shotgun shells and special explosive charges used to blow out door locks lying on the ground," Reuters reported.

Leaders of Muslim Clerics' Association have repetitively called for the withdrawal of the U.S. forces from Iraq and boycotted the country's parliamentary elections held on December 15.