On Monday, a suicide bomber killed 13 and injured 15 people at the same location near the Harthiyah gate on the western edge of the zone, which has been repeatedly targeted by bombings and mortar and missile attacks since it became the headquarters of the occupation authorities in May 2003.
In western Iraq, two U.S. Marines were killed in action, the military said Tuesday, bringing the number of Marines killed in the region over three days to 10.
A military statement said the two Marines were assigned to the 1st Marine Expeditionary Force and died Monday "while conducting security and stabilization operations" in the vast Anbar province west of Baghdad, which includes the battleground cities of Fallujah and Ramadi.
Seven other Marines died in action Sunday in Anbar and a 10th was killed on Saturday. The U.S. military did not provide details of their death, but they brought to nearly 1,300 the number of American troops killed in Iraq since the invasion in March 2003.
In other recent developments:
As insurgents pressed forward with attacks ahead of next month's elections, the country's interim president Ghazi al-Yawer told British Broadcasting Corp. radio, that "as soon as we have efficient security forces... we can see the beginning of the withdrawal of forces from our friends and partners and I think it doesn't take years, it will take months."
U.S. military commanders, however, say American forces will be in Iraq for several years and that troop numbers will rise from 138,000 to 150,000 before the Jan. 30 national elections, which many Iraqis fear could be targeted by militants opposed to the occupation and bent on derailing the political process.
Despite repeated forecasts in the past that successes on the battlefield and the arrests of most of former dictator Saddam Hussein's top lieutenants would weaken the insurgency, the number of attacks on U.S. troops and the interim government's security forces has not decreased.
About 550 U.S. soldiers died in the first year after the invasion was launched; almost 750 troops have died in the nine months that followed.
Joint Chiefs of Staff chairman, Gen. Richard Myers, arrived Tuesday in Iraq for a morale boosting visit to the troops. U.S. celebrities, including actor Robin Williams, former Denver Broncos quarterback John Elway and sportscaster Leeann Tweeden, accompanied him.
"Our troop levels will be at 150,000 for the elections and a little bit after," Myers said, adding that events on the ground would determine whether those numbers will be scaled down after the ballot.
Myers predicted that last month's U.S.-led offensive to retake the western rebel stronghold of Fallujah would undercut the rebellion by denying the guerrillas a sanctuary from which they could launch attacks with relative impunity.
"They will try to move to other locations but I don't think they are going to find any location as satisfactory as Falluajh was for their operational planning and facilitation of what they were doing."