Baghdad: Dozens of supporters of powerful Iraqi cleric Moqtada Sadr on Monday stormed the Republican Palace, a ceremonial building inside Baghdad's fortified Green Zone of government buildings, a security source said.

Angry protesters "entered the Republican Palace" shortly after Sadr said he was quitting politics, the source said, with several thousand other Sadr loyalists heading towards the Green Zone, an AFP journalist reported.

The army has announced a Baghdad-wide curfew to start from 3:30 pm (1230 GMT).