The widely separate attacks occurred as many Christians marked Easter and underscore the fragile security situation in Iraq despite a decline in violence over the past year.

About 10 detonations were heard starting shortly before 6 a.m in the sprawling Green Zone area in central Baghdad, which houses the U.S. and British embassies and the Iraqi government headquarters. Several other mortars or rockets slammed into the area about four hours later.

There were no reports of casualties inside the Green Zone, located on the west bank of the Tigris River that bisects the city. But one round fell short and exploded in a major traffic circle on the east side of the river, injuring two bystanders, police said.

The U.S. public address system in the Green Zone warned people to "duck and cover" and to stay away from windows following the first attack.

There were no claims of responsibility for the attacks. But it appeared the rounds were fired from areas of eastern Baghdad where the biggest Shiite militia, the Mahdi Army of cleric Muqtada al-Sadr, operates.

Al-Sadr called a cease-fire in August, but there are fears it may unravel after a series of clashes between U.S. and Iraqi forces and militiamen in Baghdad, Kut and other areas south of the capital.

The suicide car bomber in Mosul struck a group of armored vehicles parked outside the military post. Suicide bombings historically have been the work of Sunni extremists, and the U.S. has said the city, 360 kilometers (225 miles) northwest of Baghdad, is the last urban stronghold of al-Qaida in Iraq.

The attacks in the Green Zone coincided with Easter services, but followed a series of clashes between U.S and Iraqi forces in neighborhoods west of the Green Zone.

Last month, the U.S. military blamed what it calls Iranian-backed Shiite militias for a series of deadly rocket attacks in Baghdad. Those included one that struck Camp Victory, the main U.S. military headquarters, and an Iraqi housing complex on the capital's southwestern outskirts on Feb. 18, killing at least five people and wounding 16, including two U.S. soldiers.

The military said the extremists were among factions that have broken with al-Sadr and refused to follow his cease-fire order. Iran denies allegations that it is stoking the violence. Al-Sadr has extended the cease-fire through mid-August.

The cease-fire, along with an increase in U.S. troop levels and a move by American-backed Sunni fighters to turn against their former al-Qaida in Iraq allies, have been credited with sharply reducing violence in Baghdad and surrounding areas.

The Green Zone, a 10-square-kilometer (4-square-mile) area on the west bank of the Tigris River, houses the U.S. and British embassies, the Iraqi government headquarters and thousands of American troops. It has been frequently struck by rockets and mortar rounds fired by Shiite and Sunni extremists, though the attacks have tapered off in recent months amid stepped up security measures.

On July 10, extremists unleashed a barrage of more than a dozen mortars or rockets into the Green Zone, killing at least three people - including an American - and wounding 18.

The attacks in the Green Zone also comes as the U.S. military death toll in Iraq nears 4,000.

On Saturday, U.S. officials said three American soldiers were killed north of Baghdad. Two of the soldiers were killed in the blast and the third died of wounds, a statement said. The soldiers were assigned to Multinational Division-Baghdad, the statement said, but gave no further details.

The latest deaths brought to 3,996 the number of U.S. service members and Pentagon civilians who have died since the war began on March 20, 2003, according to an Associated Press count.

Two Iraqi civilians also died in the roadside bombing, which occurred as the Americans were patrolling an area northwest of the capital, the U.S. military said in a statement.

In other violence, a suicide bomber late Saturday drove a truck laden with explosives into the home of the mayor in Samarra, 95 kilometers (60 miles) north of Baghdad. Three security guards were killed and four others injured, police said.

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