Shia militias clashed with Iraqi and US forces in Baghdad on Friday and 10 worshippers died in a bomb blast outside a Sunni mosque in the village where a US air strike killed Abu Musab al-Zarqawi this month.
Iraqi Prime Minister Nuri al-Maliki slapped a sudden curfew on the capital after the clashes broke out there but lifted the ban on vehicles and people hours later.
In Iraq's second city of Basra, a car bomb killed five people at a petrol station, hospital sources said. Earlier, police said 10 had died in the blast, which came despite a state of emergency declared last month to end militia violence.
Underscoring the challenges Maliki faces in easing violence that has pushed Iraq to the brink of civil war, militias loyal to radical Shia cleric Moqtada al-Sadr exchanged fire with gunmen in the former Sunni insurgent stronghold of Haifa Street.
Iraqi and US forces who rushed to the area became involved in the fighting, police sources said. A Reuters cameraman saw militiamen from Sadr's Mehdi Army running across the street 200 metres (yards) from a US Humvee. Sadr, whose followers are members of the ruling Shi'ite Alliance, has staged two revolts against US and Iraqi troops.
As mortar bombs crashed and gunfire crackled in central Baghdad, Maliki, who took office last month, imposed a curfew banning people and cars from the streets from 2 pm until 6 am on Saturday. It was lifted two hours after it was declared, Maliki's office said.
State television quoted General Abdul Aziz Mohammed, operations chief at the Defence Ministry, as saying the curfew was a response to the fighting. Three Iraqi policemen and five Iraqi army soldiers were wounded. The violence later subsided.
There was no immediate comment from the US military, which launched a sweep last year to root out rebels in Haifa Street. The bomb outside the mosque went off in Hibhib, north of Baghdad, where Zarqawi, leader of al Qaeda in Iraq, was killed on June 7.
PRISONERS FREED: The US military released about 500 prisoners from the Abu Ghraib prison near Baghdad under an Iraqi government "national reconciliation" drive to free a total of 2,500 inmates. Most prisoners have been held without charges and are members of the Sunni minority, which forms the backbone of Iraq's insurgency.
Maliki, who has pledged "maximum force" against rebels but has also reached out to Sunnis to draw them into the US-backed political process, will present a national reconciliation bill to parliament on Sunday, government officials have said.