Baghdad (AFP) - Fighting between rival Iraqi forces raged for a second day Tuesday with rocket fire echoing from Baghdad's Green Zone where 23 supporters of powerful Shiite leader Moqtada Sadr have been shot dead, medics said.
Tensions have soared in Iraq amid a political crisis that has left the country without a new government, prime minister or president for months.
They escalated sharply after Sadr's supporters on Monday afternoon stormed the government palace inside the high-security Green Zone following their leader's announcement that he was quitting politics.
The violence pitches backers of Sadr against rival Shiite factions backed by neighbouring Iran, with the sides exchanging gunfire across barricades -- violence the United Nations warns risks tipping the war-ravaged country deeper into chaos.
Overnight, shelling targeted the Green Zone that houses government buildings and diplomatic missions, a security source said, amid angry protests after Sadr's surprise announcement.
Sadr, a grey-bearded preacher with millions of devoted followers who once led a militia against American and Iraqi government forces after the 2003 US-led overthrow of dictator Saddam Hussein, announced Monday his "definitive retirement" and said he had "decided not to meddle in political affairs".
On Tuesday morning, fresh clashes broke out between Sadr's supporters and the army and men of the Hashed al-Shaabi, former Tehran-backed paramilitaries integrated into the Iraqi forces.
The rattle of automatic gunfire and heavier explosions of rocket-propelled grenades could be heard from the Green Zone.
'Dangerous escalation'
The United Nations mission in Iraq warned of "an extremely dangerous escalation" and called on all sides to "refrain from acts that could lead to an unstoppable chain of events".
"The very survival of the state is at stake," it warned.
But amid an army-imposed nationwide curfew that continued Tuesday, Baghdad was otherwise quiet, with shops shuttered and few cars venturing out on the streets.
On Tuesday morning, medics updated the toll of Sadr supporters killed to 23, with some 380 others injured -- some with bullet wounds and others suffering tear gas inhalation.
A mass funeral was held Tuesday in the Shiite holy city of Najaf for some of the protesters killed in Baghdad.
Witnesses said earlier that Sadr loyalists and supporters of a rival Shiite bloc, the pro-Iran Coordination Framework, had exchanged fire.
The Framework condemned an "attack on state institutions", urging the Sadrists to engage in dialogue.
Caretaker Prime Minister Mustafa al-Kadhemi said "security or military forces, or armed men" were prohibited from opening fire on protesters.
'Disturbing'
The United States also urged calm amid the "disturbing" reports, while France called on "the parties to exercise the utmost restraint".
Shortly after Sadr made his announcement to step down, his followers burst into the Republican Palace in Baghdad -- where cabinet meetings are usually held -- and initially celebrated including by cooling off in a swimming pool in the garden.
Sadr -- a longtime player in the war-torn country's political scene, though he himself has never directly been in government -- announced he was quiting politics two days after he said "all parties" including his own should give up government positions in order to help resolve the political crisis.
His bloc emerged from last year's election as the biggest in the legislature, with 73 seats, but short of a majority.
In June, his lawmakers quit in a bid to break the logjam, which led to the Coordination Framework becoming the largest bloc.
Hamzeh Hadad, from the European Council on Foreign Relations, said it was "not clear" what Sadr's strategy was.
"Whatever it does mean, in typical Sadrist fashion, there is always backtracking expected," Hadad said.
"The second, and more terrifying thought on this is that he is giving his followers the green light to do whatever they like."
Iraq has been mired in political deadlock since legislative elections in October last year due to disagreement between Shiite factions over forming a coalition.
Sadr's supporters have for weeks been staging a sit-in outside Iraq's parliament, after storming the legislature's interior on July 30, demanding fresh elections be held.
The Coordination Framework wants a new head of government to be appointed before any new polls are held.
