BAGHDAD, Sept. 25 (Xinhua) -- Five insurgents were killed during an operation conducted by the Iraqi security forces in the volatile province of Diyala on Thursday, a provincial police source said.

    The incident occurred in the dawn when a joint force of U.S. troops and Iraqi security forces raided and surrounded a house believed to be a hideout of al-Qaida militants in the town of Mandili, some 180 km northeast of Baghdad, the source told Xinhua on condition of anonymity.

    During the raid, a fierce clashes erupted between the joint force and gunmen in the house, the source said, adding that an explosion took place inside the house, believed to be that one militant blew up his explosive vest, killing himself and four other gunmen.

    Earlier in the day, an Iraqi Interior Ministry source said that the death toll from a Wednesday ambush against Iraqi security forces in Diyala rose to 35 security members in the al-Dulaimat village, some 30 km south of the provincial capital Baquba.

    He said that 27 policemen and eight Awakening Councils group fighters were killed in the battle which broke out at about 3:30 p.m. (1230 GMT) on Wednesday when suspected al-Qaida militants ambushed an Iraqi-U.S. joint force during an operation in the village seeking al-Qaida suspects.

    Diyala has been the hotbed of terrorist operations since the U.S.-led invasion of Iraq in 2003, teeming with bombings and other types of attacks.

    The U.S. troops and Iraqi security forces have been launching multiple major operations in the region.