Nearly 10 months on from elections, the oil-rich country still has no government and no new prime minister or president.

"We appeal to all actors to commit, actively engage and agree on solutions without delay", the United Nations Assistance Mission for Iraq (UNAMI) said in a statement.

"Leaders must prioritise (the) national interest," it said.

On Wednesday, followers of powerful Shiite Muslim preacher and political kingmaker Moqtada Sadr continued a mass sit-in at parliament for a fifth day.

The Sadr bloc opposes a nomination for prime minister by the Coordination Framework, a rival, Iran-backed Shiite faction.

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 spoke with President Barham Saleh.

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

"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.

On Tuesday, a top Sadrist official gave followers 72 hours to shift their protests from the main meeting halls of parliament to the entrance of the building and a surrounding encampment.

"Iraq is facing an extensive list of outstanding domestic issues: it is in desperate need of economic reform, effective public service delivery as well as a federal budget -- to name a few," the UN added.

"Hence, it is past time for political stakeholders to assume their responsibilities and act in the national interest."

Iraq is the second largest producer in the Organization of the Petroleum Exporting Countries and derives 90 percent of federal revenue from oil.

But it has still not adopted its budget for 2022.

In June, parliament passed an emergency finance bill, to ensure gas supplies and buy grain for "food security".