Iraqi security forces opened fire on Wednesday to disperse protesters gathered on a bridge in central Baghdad, shooting live bullets in the air, a Reuters witness said. There appeared to be no casualties.

Protesters had blocked the Shuhada bridge since Tuesday afternoon as part of efforts to bring the country to a standstill, with thousands joining anti-government demonstrations in the capital and southern provinces

"More youth started gathering so they kept firing tear gas and live bullets. Maybe four were injured. We didn't do anything but they came and arrested everyone. The youth are peaceful from the start of the sit-in," said Qusay Mahdi, a protester on Shuhada Bridge.

Demonstrators run after Iraqi security forces fired tear gas during the ongoing anti-government protests in Baghdad, Iraq November 6, 2019. (Photo: Reuters)

Security forces opened live fire again later on Wednesday, this time to prevent protesters from blocking a fifth bridge.

More than 260 Iraqis have been killed in demonstrations since the start of October against a political class they see as corrupt and beholden to foreign interests. In the 24 hours to late Tuesday, security forces shot dead at least 13 protesters.

Iraqis have been congregating in Baghdad's Tahrir Square for weeks, demanding an overhaul of the political system in the biggest wave of mass protests since the fall of Saddam Hussein in 2003.

Demonstrators look at a burnt motorbike, which was burned last night during the ongoing anti-government protests in Basra, Iraq November 6, 2019. (Photo: Reuters)

Thousands have also been gathering in the impoverished southern Shi'ite heartland.

Protesters on Wednesday blocked the entrance to the Nassiriya oil refinery in the oil-producing southern province of Basra, security and oil sources said. They stopped tankers that transport fuel to gas stations from entering the refinery, causing fuel shortages.

Security forces forcibly dispersed a sit-in there overnight but no deaths were reported, security sources said. Protesters had camped out in front the provincial government building.

In a televised address on Tuesday, Prime Minister Abdul Mahdi said the protests were having an economic impact the country could not afford, and he asked demonstrators to refrain from further damaging public and private property.

Security sources said on Wednesday that arrest warrants for protest organisers arrived from Baghdad to all provinces on Tuesday. Dozens have already been arrested in Basra and Nassiriya, they said.

Employees of Iraq central bank leave their workplaces in central Baghdad, Iraq, Wednesday, Nov. 6, 2019. Iraqi security forces deployed in large numbers around the bank and began evacuating employees from the building. The protesters did not appear to be heading toward the bank itself. (Photo: AP)

The U.S Embassy in Baghdad on Wednesday condemned the deadly violence against unarmed demonstrators, and urged Iraq's leaders to engage urgently with the thousands who have been protesting.

"We deplore the killing and kidnapping (of) unarmed protesters, threats to freedom of expression, and the cycle of violence taking place. Iraqis must be free to make their own choices about the future of the nation," it said in a statement.

Young Iraqis walk past colourful murals in Baghdad's Tahrir Square as the Iraqi capital braces for another day of anti-government protests on November 6, 2019. (Photo: AFP)

An Iraqi protester sleeps during an anti-government demonstration in the capital Baghdad's Tahrir Square on November 6, 2019. (Photo: AFP)

Anti-government protesters block the port of Umm Qasr, south of Basra, Iraq, Tuesday, Nov. 5, 2019, as Iraqi security forces try to reopen the country's main ports. (Photo: AP)

Iraqi men carry the coffin of a demonstrator reportedly killed earlier outside the Iranian consulate, during his funeral in the Shiite shrine city of Karbala, south of Iraq's capital Baghdad, on November 4, 2019. (Photo: AFP)

This picture taken on November 4, 2019 shows a building under construction that has been taken over by Iraqi anti-government protesters and draped with national flags and protest signs and slogans, in Nasiriyah, the capital of the southern province of Dhi Qar. (Photo: AFP)