A heavy cloud of smoke rises during fierce fighting between insurgents and Iraqi security forces, backed by US troops, around Haifa street in central Baghdad. More than 50 gunmen were killed during a fierce battle on Tuesday. (Xinhua/AFP Photo) Photo Gallery >>>

    BAGHDAD, Jan. 9 (Xinhua) -- Iraqi forces backed by U.S. troops and aircraft killed up to 50 gunmen during a fierce battle with gunmen in central Baghdad on Tuesday, a Defense Ministry spokesman said.

    Major Gen. Ibrahim Shaker told reporters that the joint U.S. and Iraqi troops detained 21 militants, including three Syrians and one Sudanese.

    Early in the morning, fierce clashes broke out after Iraqi soldiers carried out a search operation in a Sunni neighborhood around Haifa Street in central Baghdad and government forces called in U.S. military support to control the area, a police source said.

    A U.S. military statement said the U.S.-Iraqi forces were "conducting targeted raids to capture multiple targets, disrupt insurgent activity and restore Iraqi security forces control of North Haifa Street."

    "This area has been subject to insurgent activity which has repeatedly disrupted Iraqi security force operations in central Baghdad," said Lt. Col. Scott Bleichwehl, spokesperson for Multi-National Division Baghdad.

    The joint forces received small arms fire, rocket-propelled grenade and indirect fire attacks during the operation, he said.

    Since late Saturday, tension has mounted in the neighborhood following an operation by Iraqi troops in which 30 militants were killed and eight others detained, including five Sudanese fighters, according to the state-run Iraqia TV.