Bodyguards for Iraq's deputy prime minister wounded two people when they fired warning shots at Sunni protesters who pelted his convoy with bottles and stones on Sunday, witnesses said.
The incident took place the city of Ramadi in western Anbar province, to where Deputy Prime Minister Saleh al-Mutlaq had travelled to address people in an attempt to defuse sectarian tensions.
Thousands of Iraqi Sunnis have taken to the streets and blocked a main highway over the past week in protest against Shi'ite Prime Minister Nuri al-Maliki, whom they accuse of discriminating against their community and being under the sway of non-Arab neighbour Iran.
"Leave! Leave!" the protesters shouted at Mutlaq, himself a Sunni.
Mutlaq's guards opened fire to disperse the crowd after they threw objects at his convoy. Two people were wounded, the witness said
"It's only now Mutlaq comes to attend the protest and after seven days. He came to undermine the protest," Saeed al-Lafi, a spokesman for the protesters, told Reuters.
Protesters are demanding an end to marginalisation of Iraq's Sunni minority, which dominated the country until the U.S.-led invasion of 2003 that toppled Saddam Hussein.
They want Maliki to abolish anti-terrorism laws they say are used to persecute them.
Echoing slogans used in popular revolts that brought down leaders in Egypt, Yemen, Tunisia and Yemen, protesters have also been calling on Maliki to step down.
"Is this the way to deal with peacful protesters? To shoot them? This is really outrageous," said protester Ghazwan al-Fahdawi, displaying empty bullet casings from shots he said had been fired by Mutlaq's guards.
In the northern city of Mosul, the provincial council called a three-day strike starting from next Friday to press Baghdad to release women prisoners and stop targeting Sunni politicians.
Protests flared last week in Anbar province after troops loyal to Maliki detained bodyguards of his finance minister, a Sunni.
That came just hours after Iraqi President Jalal Talabani, a Kurd seen as a steadying influence on the country's tumultuous politics, was flown abroad for medical care.
A year after U.S. troops left, sectarian friction, as well as tension over land and oil between Arabs and ethnic Kurds, threaten renewed unrest and are hampering efforts to repair the damage of years of violence and exploit Iraq's energy riches.