At least four people were killed and 48 wounded on Thursday (November 21) after Iraqi security forces fired tear gas at protesters occupying key bridges in Baghdad.

Medical and security sources said some of the protesters were killed by live fire and tear gas canisters aimed directly at the head.

Hospital sources said some of the wounded sustained wounds from live ammunition and others from rubber bullets and tear gas canisters.

Protesters have constructed makeshift barricades on three major bridges in central Baghdad which lead to the city's fortified Green Zone, where government buildings and foreign embassies are located.

More than 300 people have been killed since the start of mass unrest in Baghdad and southern Iraq in early October, the largest demonstrations since the fall of Saddam Hussein in 2003.

Deadly use of live ammunition, tear gas and stun grenades against mostly unarmed demonstrators have stoked the unrest.

The protests are an eruption of public anger against a ruling elite seen as enriching itself off the state and serving foreign powers, especially Iran, as many Iraqis languish in poverty without jobs, healthcare or education.