Caretaker Prime Minister Mustafa al-Kadhemi cut short a visit to Egypt where he had been due to take part in a five-nation summit, to return home to monitor developments in his country, which has been mired in political deadlock for months.

Kadhemi "called on all political parties to calm down and to take advantage of the opportunity for national dialogue to get the country out of its current crisis", his office said.

The standoff between the Sadrists and their rivals in the pro-Iran Coordination Framework has triggered an intensifying war of words, but so far no violence.

The Sadrists, who have already been camped outside parliament for the past three weeks, pitched tents outside the gates of the judicial body's headquarters in Baghdad on Tuesday morning.

They carried placards demanding the dissolution of parliament and new elections, 10 months after an inconclusive poll failed to deliver a majority government.

The country is still waiting for a new government, premier and president.

But the sit-in began to draw down in the evening after a close associate of Sadr's, Saleh Mohamed al-Iraqi, called on protesters to pull back.

About 10 hours after it began, demonstrators were encouraged to withdraw "while keeping tents up", but were told they could "continue the sit-in in front of parliament" if they wished.

An AFP journalist saw protesters leaving the area.

- 'Stamp out corruption' -

Though Sadr's political bloc has taken part in previous administrations, securing top jobs in government ministries, Sadr himself has managed to largely keep above the political fray.

He is lionised by his supporters as an outsider dedicated to the fight against a corrupt elite.

"We want to stamp out corruption," said Abu Karar al-Alyawi, a Sadr supporter among those demonstrating.

"The judicial system is being blackmailed, or maybe it's corrupt too."

On August 10, Sadr gave the Supreme Judicial Council one week to dissolve parliament to end the political deadlock, but the council ruled it lacked the authority to do so.

The council had initially announced it was suspending operations amid the protest, but as it calmed, judges said they would resume work on Wednesday.

The UN mission in Iraq said it respected the right to "peaceful protest", while urging "respect for state institutions".

- Talks boycotted by Sadrists -

Police deployed in numbers around the headquarters, which unlike parliament, lies outside Baghdad's high-security Green Zone government and diplomatic compound.

Following the start of the sit-in, the Coordination Framework said it would "refuse any call for direct dialogue" with the Sadrists, until they put an end to "the occupation of institutions".

The Coordination Framework, which has been holding a sit-in of its own just outside the Green Zone, wants a transitional government before new polls are held.

The alliance includes former paramilitaries of the Tehran-backed Hashed al-Shaabi network, and the party of ex-prime minister Nuri al-Maliki, a longtime Sadr foe.

The Hashed late Tuesday said it was ready to "defend state institutions".

Kadhemi, the prime minister, last week convened crisis talks with party leaders, but they were boycotted by the Sadrists.

Since the aftermath of the US-led invasion of 2003, Iraq has been governed under a sectarian power-sharing system that reserves the premiership for the country's Shiite majority community.

The Sadrists insist that after emerging from 2021 elections as the largest bloc in parliament -- but not an absolute majority -- the constitution be amended to give it the right to nominate the prime minister, something their opponents strongly oppose.

The persistent failure of the rival Shiite factions to form a government in a country blighted by ailing infrastructure and crumbling public services has sparked mounting public frustration.

Iraqis grown used to daily power cuts lasting much of the day now also face water shortages as drought ravages swathes of the country.

Despite its oil wealth, many Iraqis are mired in poverty, and some 35 percent of young people are unemployed, according to the United Nations.