The Iraqi authorities will be imposing a nationwide curfew at 19:00 local time (16:00 GMT) on Monday until further notice, the Iraqi Security Forces Joint Command said in light of ongoing widespread protests.

"Complete ban on movement in all provinces of Iraq from 19:00 today until further notice," the statement said.

The Iraqi Joint Operational Headquarters issued a statement announcing a lockdown as of 15:30 local time (12:30 GMT) in light of fears of an escalation, calling on the security services to bolster the protection of governmental buildings, banks, political parties' headquarters, and infrastructure.

Hundreds of the Sadrist movement's followers broke into Baghdad’s green zone shortly after the movement's leader, Muqtada Al-Sadr, announced his retirement from politics. 

An AFP correspondent reported that the protestors broke into the meeting rooms in the governmental buildings, and some of them carried the Iraqi flag while others swam in the Republican Palace's swimming pool.

The correspondent also reported seeing thousands of supporters of the Sadrist movement in the streets of Baghdad outside the Green Zone, heading toward the official presidential residence.

"There are fears of the developments spreading out to Basra after the demonstrators blocked the Algerian street intersection," the chief of Al Mayadeen's bureau in Baghdad.

Local media reported that the security forces resorted to using tear gas to disperse protestors gathered around the Presidential Palace.

Leader of the Sadrist movement Muqtada Al-Sadr said earlier today that he was quitting politics. In a tweet, Sadr announced his final resignation from politics and the closure of all his party offices.

He added that "all the institutions" linked to his Sadrist movement will be closed, except the mausoleum of his father, Mohammed Sadeq Al-Sadr, who was assassinated in 1999, and other heritage facilities.

Al-Sadr's supporters have been staging a sit-in outside Iraq's parliament for several weeks, after storming it on July 30 to protest the Coordination Framework's nomination of Mohammad Shiya Al-Sudani for Prime Minister.

Caretaker Prime Minister Iraqi Prime Minister Mustafa Al-Kadhimi convened talks with party leaders earlier this month, but the Sadrists shunned them.