`Anti-government protesters packed into the Iraqi capital's Tahrir Square late Tuesday in the largest numbers yet as the political crisis sparked by their demonstrations deepened further.
Late into the night, blaring horns, fireworks and loud Iraqi music filled the plaza, the capital's focal point for demonstrations over unemployment and corruption that have escalated into calls for the government to quit.
The rallies have swelled in recent days, defying curfews, threats of arrest and violence that has left 242 people dead and more than 8,000 wounded this month.
"We've started fighting over who can kick back the tear gas canister first," said Youssef, a 33-year-old who was spending his sixth straight night in the square.
"They won't be able to suppress these protests."
Security forces have fired volleys of tear gas at crowds massing on a key bridge linking Tahrir Square to the Green Zone, which hosts government offices and foreign embassies.
The chaotic protest movement is unprecedented in Iraq, both because of its apparently independent nature and the ensuing violence.
The first burst of protests starting October 1 left 157 people dead, mostly protesters in Baghdad. At least 83 more have died in a second wave starting Thursday.
They included at least one protester killed overnight in the Shiite holy city of Karbala, according to the Iraqi Human Rights Commission.
The Karbala violence has sparked condemnations from Amnesty International, who said "excessive and often lethal force" was used against protesters "in a reckless and utterly unlawful manner."
Cycle of violence
"The vicious cycle of violence must end," said the United Nations' top official in Iraq Jeanine Hennis-Plasschaer, urging a national dialogue to respond to protesters' demands.
Thus far, the government's reform proposals -- hiring drives, anti-corruption campaigns and more social safety nets -- have failed to appease protesters.
Their demands have been championed by Moqtada Sadr, a Shiite religious leader and ex-militiaman with a cult-like following in parts of Iraq.
But Sadr himself is one of the current government's two main sponsors, after his Saeroon bloc won the largest share of parliament's 329 seats in a vote last year.
On Tuesday, he returned to his native Najaf, a holy city in southern Iraq, shortly after airport sources told AFP he had landed from neighbouring Iran.
In a surprise move, he then invited rival Hadi al-Ameri, who leads the second-largest parliamentary bloc Fatah, to secure the votes needed for snap elections.
Hours earlier, Abdel Mahdi had sent an open letter to Sadr dismissing his calls for the premier to resign and challenging him to find a political solution.
"If the goal of elections is to change the government, then there is a shorter way: for you to agree with Mr. Ameri to form a new government," Abdel Mahdi wrote.
That government could then begin work within "days, if not hours," said the premier.
Later, Sadr shot back: "I thought asking you to call for early elections was a way to preserve your dignity."
"But if you refuse, I call on Hadi al-Ameri to work together to withdraw (parliament's) confidence from you immediately," he wrote on Twitter.
That would necessitate early polls.
Youth turns up heat
Sadr and Ameri formed a strained alliance to bring Abdel Mahdi to power last year, but have found themselves on opposite sides of this month's protests.
Fatah is the political arm of the Hashed al-Shaabi paramilitary force, which has publicly backed the government.
Several Hashed offices were torched in southern Iraq last week in what observers said was an escalation of that rivalry.
There was no immediate comment from Ameri on Sadr's invitation.
Abdel Mahdi has thus far ignored calls from parliament for him to come in for questioning "immediately", a day after it agreed to explore early polls and constitutional amendments.
The protests recently received a new push by Iraq's younger generation, with students and school children streaming into the streets despite orders to return to class.
Trade unions representing teachers, lawyers and dentists have all declared strikes lasting several days.
About 60 percent of Iraq's 40-million population is under the age of 25.
But youth unemployment stands at 25 percent, while one in five live below the poverty line, despite the vast oil wealth of OPEC's second-largest crude producer.
"We don't want this government any more. We want a transitional government and constitutional change," another female protester said.
"I'm a teacher, I have a salary, I have a house -- but the young unemployed people are my brothers and relatives, too."