Iraqis were readying for potentially tense Friday prayers after a week of mounting anger over the bloodshed that saw at least 16 Iraqi protesters shot dead by US forces.
The killings in the city of Fallujah west of Baghdad have enflamed sentiment over the US occupation of the country and the general chaos that still reigns more than three weeks after Saddam Hussein was toppled.
Residents said a rally was expected after prayers while local religious leaders say they are appealing for calm in the city, a hotbed of Sunni Muslim hardliners as well as loyalists to Saddam's once all-powerful Baath party.
"Some former Baath party members are planning to make things unstable again in Fallujah. We know that they don't want peace in the city," said Taha Hamid al-Alawi, the local representative of the provincial governor.
"Many of the reasonable people in Fallujah want the Americans to stay and to restore security. The only thing is, we don't want them near sensitive buildings like mosques," he said.
Thirteen people were killed at anti-US rally on Monday and three more shot dead in a similar incident Wednesday.
US troops said they had come under fire from the crowd and some residents have said provocateurs disrupted what had been peaceful marches.
Seven US troops were injured in a grenade attack in the city Thursday, and public rage and frustration over the US presence, and the ongoing lack of basic needs like water and electricity, appears to be on the boil.
Local firemen were completely overwhelmed by a fire at a Baghdad petrol station on Thursday that killed at least seven people. Unable to put out the blaze hours later, they asked US troops to effectively bury the site.
But many in the crowd that gathered erupted in fury when the soldiers blocked access to the site and they could not be calmed until the troops explained they were being kept back for their own safety.
The misunderstanding highlighted one of the difficulties for the American troops trying to keep order in the nation, much of which is in a political vacuum in the aftermath of the US-led war.
Political delegates hand-picked by the United States have agreed on a national political congress next month to lay out an interim government, but there has been no sign of a consensus or when it could take over power.
The weeks after Saddam was toppled in Baghdad on April 9 have seen a profusion of weapons in streets and markets, uncertainty over who is in control in many areas and ongoing robberies and looting.
In the southern holy city of Najaf, where a leading pro-Western Shiite was assassinated last month just days after returning from exile, five men Friday shot at a police station where they believed his suspected killers were being held.
Police said the men retreated after a firefight and that no officers were injured. Two people were arrested in Najaf on Thursday in connection with the murder and 14 others are still sought.
The instability gripping the country has heightened the difficulties for Jay Garner, the retired US general who is overseeing the reconstruction of the country.
US media reported that Garner will now report to a career diplomat and security expert, Paul Bremer, said to be on the verge of being named as the new civilian administrator for Iraq by US President George W. Bush.
As Garner had been the top US civilian overseeing post-war Iraq, it was not clear what the change would mean for the US team administering the country.
Bush on Thursday made a dramatic address aboard an aircraft carrier at sea to announce the end of major combat operations in the Iraq war. He said "dangerous work" still remained to be done.
The US military said this week that thousands more soldiers would be poured into Baghdad in the coming days to try to help restore order.
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