US troops in Iraq's holy city of Karbala have clashed with fighters loyal to the radical Shia cleric Moqtada Sadr.
Clashes took place close to the Imam Hussein holy site
Hospital officials said one Iraqi fighter was killed and as many as 13 Iraqis injured.
About 1,000 people in the city took part in a demonstration on Sunday to protest against the US-led occupation.
At one point they met a column of US tanks as it drove through the city, home to important Shia Muslim shrines.
Sunday's clashes took place close to the revered Imam Hussein and Imam Abbas shrines.
Up to 15 US tanks took up position near the shrines while helicopters flew ahead.
Chanting "no to colonialism", the protesters called for US troops to pull back from the areas close to the shrines.
Day of bloodshed
There are also reports of two Iraqis killed and two wounded in Najaf, the holy city close to Karbala.
Further south, in the Iraqi second city of Basra, at least three Iraqi civilians were killed in a rocket attack close to a British military base. Two-year-old twin girls were reported to be among the dead.
And reports say two Iraqi fighters were killed and six Italian soldiers wounded in clashes in the southern city of Nasiriya.
In the capital Baghdad, two Iraqi women working for the coalition were killed when their vehicle came under fire by gunmen. Their driver was also killed.
The US military said on Sunday that one of its soldiers had died in an overnight roadside bomb blast. A second soldier was wounded.
In a separate incident, a US soldier has died from wounds suffered during a firefight south of Baghdad on Saturday.
In neighbouring Iran, Supreme leader Grand Ayatollah Ali Khamenei, said the US incursions in Najaf and Karbala were "shameless".
It was time for the US to leave the "bog of their own making", he said in a speech.
In the Iranian capital, about 200 students threw stones at the British embassy and chanted slogans against the occupation of Iraq and torture of prisoners.
Correspondents say Iran's clerical leadership has until recently been muted in its criticism of the US-led invasion and occupation of Iraq.
Dozens of people have been killed in clashes between the US-led coalition and Moqtada Sadr's Mehdi Army since Friday.
Mr Sadr, who launched an uprising last month, is wanted by the US in connection with the assassination of a rival Shia cleric.