File photo shows a U.S. helicopter near a U.S. base in Iraq. (Xinhua/AFP Photo) Photo Gallery >>>

    BEIJING, Jan. 22 (Xinhuanet) -- Four U.S. soldiers and a Marine were killed Saturday during combat in Anbar, a roadside bomb struck a security patrol northeast of Baghdad, killing one soldier, 12 soldiers died in a Blackhawk helicopter crash northeast of Baghdad, five were killed in a militant attack in the holy Shiite city of Karbala and two others slain elsewhere in roadside bombings as 25 soldiers were killed in the deadliest day for U.S. troops in Iraq in two years.

    The dramatically rising death toll among U.S. forces comes at a critical time of increasing congressional opposition to President Bush's decision to dispatch 21,500 additional soldiers to the conflict.

    The U.S. military statement about the Karbala attack said "an illegally armed militia group" attacked the provincial headquarters building with grenades, small arms and "indirect fire," which usually means mortars or rockets.

    "A meeting was taking place at the time of the attack to ensure the security of Shiite pilgrims participating in the Ashoura commemorations," said a statement from Brig. Gen. Vincent K. Brooks, deputy commander of the Multi-National Division-Baghdad.

    Thousands of Shiite pilgrims are flocking to the city to mark the 10-day Ashoura festival commemorating the death of one of Shiite Islam's most sacred saints, Imam Hussein, grandson of the Prophet Muhammad.

    Provincial Gov. Akeel al-Khazaali, who was not present at the security meeting, said the gunmen were dressed in military uniforms, They were able to drive their black SUVs, similar to those driven by foreign dignitaries, through a checkpoint on the outskirts of the city, 50 miles south of Baghdad.He said police assumed it was a diplomati convoy and informed headquarters that it was coming.

    "The group used percussion bombs and broke into the building, killed five Americans and kidnapped two others, then fled," the governor said, adding that Iraqi troops later found one of the SUVs with three bodies of uniformed men.

    The U.S. military, which has said five U.S. soldiers were killed and three were wounded while repelling the attack, denied that two U.S. troops were kidnapped.

    Lt. Col. Christopher Garver, a military spokesman, said all American forces "were accounted for after the action."

    A security official in Karbala, speaking on condition of anonymity because he was not authorized to disclose the information to the media, said the gunmen drove to Babil province after the attack. The Babil police commander confirmed they entered the region before disappearing.

    (Agencies)