BAGHDAD (Reuters) - Al Qaeda's Iraqi affiliate claimed responsibility Tuesday for a daylight raid by suicide bombers on an army base in central Baghdad in which 12 people died.
U.S. forces became involved in Sunday's fighting less than a week after formally ending combat operations in Iraq.
The Islamic State of Iraq, an umbrella group for al Qaeda-linked insurgents, said in a statement posted on a radical Islamic website that five suicide bombers were involved.
The first attacker blew up an explosives-laden vehicle at the back gate of the military compound and four attackers wearing suicide vets and armed with assault rifles and grenades then stormed the compound and occupied a building, it said.
"The engagement lasted inside the compound more than an hour, when the crusaders' planes and some of their patrols became engaged," the ISI statement said, referring to U.S. troops that ended up joining the gunfight.
"God has granted to the Holy Men the killing and the wounding of dozens of treacherous officers, soldiers and security leaders and after they ran out of ammunition, they exploded their vests upon the vanguard of the disbelievers who tried to storm the building."
After Washington declared combat operations in Iraq formally over, the remaining 50,000 U.S. soldiers there will focus on advising and helping Iraqi police and troops before a full withdrawal next year. However, they will still get involved in fighting if attacked.
The attack took place just over two weeks after at least 57 Iraqi army recruits and soldiers were killed by another suicide bomber at the same compound.
Insurgents are targeting Iraqi police and troops as the U.S. military gradually pulls out more than seven years after invading. The failure of Iraqi leaders to agree a new government six months after an election has also stoked tensions.
Overall violence has fallen sharply since the height in 2006/07 of the sectarian warfare unleashed after the invasion. But attacks by a Sunni Islamist insurgency are still a daily occurrence.
The end of the U.S. combat mission has raised fears of a return to broader bloodshed.
Reporting by Khalid al-Ansary; Writing by Michael Christie; Editing by David Stamp