Amid delays in finding a new prime minister, the 89-year-old urged lawmakers to "form a new government as soon as possible," according to his representative Abdel Mahdi al-Kerbalai.

"The quickest and most peaceful way out of the current crisis and to avoid plunging into the unknown, chaos or internal strife ... is to rely on the people by holding early elections," said the representative of Sistani, who never appears in public.

Iraq has been rocked by two months of anti-government protests, the worst wave of unrest since a 2003 US-led invasion ended the reign of dictator Saddam Hussein.

The demonstrators have condemn official graft and a lack of jobs and demanded the ouster of the entire political class.

About 460 people have been killed and 25,000 wounded in street clashes in the capital Baghdad and across the Shiite-majority south.

Iraq's deeply divided parliament has been struggling to replace premier Adel Abdel Mahdi, who quit in November in the face of the mass protests and after the death toll mounted.

Parliament had been due to propose a new candidate by the end of Thursday.

But as parliamentary blocs remained deeply split, a source within the presidency said authorities had agreed to push the deadline back to Sunday, after Iraq's Friday-Saturday weekend.