Fallujah, Iraq: At least four people were killed on Friday when Iraqi troops opened fire during clashes in Fallujah city with Sunni protesters rallying against Shiite Prime Minister Nouri Al Maliki, officials and witnesses said.

It was the most serious violence since Sunni protesters began taking to the streets in late December to challenge Al Maliki’s Shiite-led government and rally against what they see as the marginalisation of their minority sect.

A Reuters witness at the scene said troops initially fired in the air to disperse crowds, but later some soldiers fired shots at protesters who approached their military vehicles and set one of them on fire.

A local television channel showed demonstrators approaching the army vehicles and throwing stones and water bottles while troops tried to keep them away began firing in the air. But it showed at least one soldier aiming his rifle at demonstrators.

The demonstrations in Fallujah, a predominantly Sunni city 50km north of capital, were part of weekly Friday anti-government rallies in the Iraqi Sunni heartland of Anbar province and other mainly Sunni areas.

Since the fall of Saddam Hussain after the US-led invasion a decade ago, many Iraq Sunnis feel they have been sidelined by the country’s Shiite leadership and believe Al Maliki is amassing power at their community’s expense.