The American embassy in Iraq says a rocket attack on Baghdad's heavily fortified Green Zone has killed four Philippine contractors working for the U.S. government.

An embassy statement Thursday said the attack took place Wednesday and that it was making the announcement "with a profound sense of sadness and regret."

It said insurgents have fired a number of rockets and mortar bombs at the Green Zone over the past few days, but until now there had been no reports of casualties.

Baghdad's Green Zone houses many Iraqi government ministries, parliament and U.S. and several other foreign missions

Separately, the U.S. military says coalition forces detained two suspected terrorists during raids in Baghdad's mainly Shi'ite Sadr City district early Thursday.

On Wednesday, a suicide car bomber killed at least nine people and wounded 34 others outside a police station in Baghdad.

Iraqi police say at least 54 others were killed or found dead nationwide.