Iraqi security forces raided Baghdad's main protest site at Tahrir Square on Saturday and tried to clear protesters in southern cities, firing tear gas and bullets that wounded more than 30 people, Reuters reporters and medical sources said.
The clashes took place after authorities began removing concrete barriers near Tahrir Square, where anti-government demonstrators have camped out for months, and across at least one main bridge over the Tigris River in the capital.
Supporters of populist cleric Moqtada al-Sadr had begun to leave protest camps overnight after he announced he would no longer be involved in the anti-government demonstrations.
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, security sources said. Police arrested at least 16 protesters in the city, they said.
At least 34 people were injured in the clashes between police and protesters in Baghdad, and another six in the southern city of Nassiriya, security sources and medics said.
The actions of the security forces appeared to be an attempt to fully clear anti-government sit-ins and end months of demonstrations calling for the removal of Iraq's ruling elite.
The raids began hours after al-Sadr said he would halt the involvement of his supporters in the anti-government unrest.
Sadr had supported the demands of protesters for the removal of corrupt politicians and for the 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 many hailing from Baghdad's slums have however been involved in the protests.
Sadr's followers held a march on Friday calling for the removal of US troops from the country in a rally separate from the anti-government protests. The march dissipated after several hours.
Sadr wrote on Twitter late on Friday 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.