Soldiers fired on an anti-government rally west of Baghdad on Friday, killing six demonstrators, the first deaths in weeks of increasingly angry protests calling for Iraq's premier to quit.
The shootings came as tens of thousands rallied in majority Sunni areas of the country, railing against alleged targeting of their minority community by the Shiite-led authorities, while in a cross-sectarian show of support, Shiite clerics called on the government to heed their demands.
Protesters had been moving to an area in east Fallujah, a predominantly Sunni town about 60 kilometres (35 miles) from Baghdad, but were blocked off by soldiers deployed from Baghdad, police Captain Nasser Awad told AFP. They began throwing bottles of water at the troops, who opened fire.
Six demonstrators were killed, all of them from gunshot wounds, said Khaled Khalaf al-Rawi, a doctor at Fallujah hospital. Rawi said 35 others were wounded, the majority of them as a result of gunfire.
Defence ministry spokesman Major General Mohammed al-Askari said an inquiry had been opened, and pledged that victims would be financially compensated.
Officials in Fallujah earlier said the army had vacated the town and had been ordered to transfer security responsibility to the police.
Mosques in Fallujah used loudspeakers to urge calm, and security forces imposed a curfew across the town.
Prime Minister Nuri al-Maliki called for restraint on the part of security forces in a statement issued by his office, but also blamed protesters for "raising tensions" and insisted the soldiers had been "attacked".
"This is what Al-Qaeda and terrorist groups are seeking to exploit," he said, referring to apparent sectarian tensions.
Similar demonstrations, meanwhile, took place in the nearby city of Ramadi, like Fallujah a mostly Sunni town in the western province of Anbar, as well as the cities of Samarra, Mosul and Baquba, all north of Baghdad.
Signup to our newsletter and follow us on Facebook and Twitter!
Rallies also took place in Sunni neighbourhoods of the capital.
The longest-running of the protests, in Ramadi, has cut off a key trade route linking Baghdad to Jordan and Syria for a month.
"The government should respond immediately to the demands of protesters, before we start a revolution and put an end to it (the government)," said Hassan al-Zaidi, a tribal chief who was protesting in Baquba.
Demonstrators in Samarra held banners calling for Prime Minister Nuri al-Maliki to quit, while protesters in Baquba called for the "fall of the regime", and held banners that read, "Iran out, Baghdad always free", referring to Sunni claims that the government is controlled by Shiite neighbour Iran.
Rallies also called for freeing prisoners who demonstrators allege are being wrongfully held, with one banner in Mosul reading, "Enough talk -- break the doors of the prisons".
Shiite clerics, meanwhile, called for the government to heed demonstrators' demands.
"There must be agreement with the demands," Sadr al-Din al-Qubanji, linked to the Supreme Iraqi Islamic Council political bloc, said in his Friday sermon in the holy Shiite city of Najaf, south of Baghdad. "Nobody can say that the government is clean from errors."
If the authorities did not work to address protesters' demands, Qubanji warned, "There is another way, which can collapse the entire political process in Iraq."
The protests have hardened opposition against Maliki and come amid a political crisis less than three months ahead of key provincial elections.
Demonstrators began by criticising the alleged exploitation of anti-terror laws to detain Sunnis wrongfully, but have since moved on to calling for the premier to quit.
The government has sought to curb the rallies by claiming to have released nearly 900 prisoners in recent weeks, with a senior minister publicly apologising for holding detainees without charge.