Iraqi security forces raided Baghdad's main protest site at Tahrir Square on Saturday, firing live rounds and tear gas at anti-government demonstrators who have camped out there for months, according to a Reuters report.

There were no immediate reports of casualties but at least seven people were wounded in clashes with police earlier in the day, medics and security sources said.

The clashes took place after authorities began removing concrete barriers near Tahrir Square and across at least one main bridge over the Tigris River in Baghdad.

In the southern city of Basra, security forces raided the main anti-government sit-in overnight and deployed in force to stop protesters gathering there again. Police arrested at least 16 protesters in Basra, according to security sources.

The actions appeared to be an attempt to fully clear out anti-government sit-ins and end months of popular demonstrations that have called for the removal of Iraq's entire ruling elite.

Security forces began the raids just hours after populist cleric Moqtada al-Sadr said he he would no longer back the anti-government unrest.

Sadr had supported the demands of protesters for the removal of corrupt politicians and provision of services and jobs soon after the demonstrations began in October, but stopped short of calling all his followers to join in.

Many of Sadr's millions of supporters who hail from Baghdad's slums have been involved in the demonstrations, however.

Sadr's followers held a march on Friday calling for a removal of US troops from the country in a rally separate from the anti-government protests. The march, which some observers expected to descend into violence, dissipated after several hours.

Sadr wrote on Twitter late on Friday that he would "try not to interfere in the issue (of protesters), either negatively or positively, so that they can shepherd the fate of Iraq." He did not elaborate.

In Basra, protesters urged Sadr to reconsider what they said was a withdrawal of support for popular demonstrations. In a letter circulated on social media, they called for the support of Sadrists, without whom they feared attacks by security forces.