Nearly 10 months on from the last elections, the country still has no government and no new prime minister or president after repeated squabbles between factions over forming a coalition.

In the latest political turmoil to strike the oil-rich but war-scarred country, Sadr called for a "revolutionary and peaceful process, then early democratic elections after a dissolution of parliament".

"I am certain that the majority of the population is exasperated by the ruling class in its entirety, including some (politicians) belonging to my movement", Sadr said.

His televised speech came as his supporters occupied parliament for a fifth consecutive day, in protest at a nomination for prime minister by a rival Shiite faction, the Iran-backed Coordination Framework.

Supporters of that rival faction have in recent days accused Sadr of attempting to launch a coup.

"From now on there will be no more old-guard politicians, whatever their affiliation," Sadr added.

Sadr, who once led an anti-US militia and who has millions of devoted followers, noted that he also had "no interest" in negotiating with his rivals.

- 'Risk of escalation' -

Surrounding parliament, the cleric's supporters have set up an encampment with tents and food stalls, and Sadr on Wednesday called on them to continue.

"The revolutionaries and protesters participating in the sit-in must stay and continue their camp until the demands are realised," he said.

The Sadrist camp was outraged by the Coordination Framework faction last week nominating former minister Mohammed Shia al-Sudani as prime minister.

The Coordination Framework is a grouping that includes former prime minister Nuri al-Maliki, a long-standing foe of Sadr, and the Hashed al-Shaabi, a former paramilitary network now integrated into the security forces.

Outgoing prime minister Mustafa al-Kadhemi has called for a "national dialogue" in a bid to bring all sides together to talk, and on Wednesday he spoke with President Barham Saleh.

Both men stressed the importance of "guaranteeing security and stability" in the country, according to the Iraqi News Agency.

Thousands of Coordination Framework supporters have held counter-protests in Baghdad against the occupation of parliament.

"Don't believe the rumours that I don't want dialogue," Sadr said Wednesday.

"But we have already tried and experienced dialogue with them," he added. "It has brought nothing to us and to the nation -- only ruin and corruption."

Earlier on Wednesday, the United Nations mission in Iraq called on leaders to put their country first and end the long-running power struggle.

"Meaningful dialogue among all Iraqi parties is now more urgent than ever, as recent events have demonstrated the rapid risk of escalation in this tense political climate," the UN mission warned.

"We appeal to all actors to commit, actively engage and agree on solutions without delay", it added, warning that "leaders must prioritise (the) national interest".