Four protesters were killed by tear gas canisters in Baghdad on Thursday as security forces try to snuff out the largest grassroots movement to sweep Iraq in years.
Iraq's political elite has come under renewed pressure in recent days from both the street and the international community to seriously address calls for sweeping reform.
There has been mounting international criticism of the authorities' response to the protests, which have left more than 330 dead since October 1.
Early Thursday, four protesters were killed by tear gas canisters near the main Baghdad protest camp in Tahrir (Liberation) Square, medical sources told AFP.
Skirmishes broke out between security forces and protesters, with clusters of young men wearing surgical masks and construction helmets tossing tear gas canisters back at riot police stationed behind concrete blast walls.
The protesters have occupied the square for three weeks, braving live rounds, stun grenades and even machine gun fire.
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Security forces have relied heavily on tear gas to confine protesters to Tahrir, but human rights groups have accused them of improperly firing the canisters directly into crowds at point-blank range, piercing protesters' skulls and chests.
"Didn't the marjaiyah (the Shiite religious leadership) say forces shouldn't use live fire? Doesn't this count as live fire?" one protester yelled angrily.
Just beside him, a demonstrator was carried away after collapsing on the ground overcome by the potent tear gas.
Thursday's deaths marked a resurgence of bloodshed after a few days of relatively peaceful protests in the capital.
The crowds in Tahrir have swelled with students and striking teachers in recent days.
In the southern hotspots of Diwaniyah, Nasiriyah, Hilla and Kut, schools and most government offices were closed on Thursday.
On Thursday, the Old City of Najaf -- one of Shiite Islam's holiest sites -- joined in with a general strike.
"We're ready to take a loss for a day, or a month, or even 20 months. We've been losing for 16 years," said one merchant.
He was referring to the time passed since a US-led invasion toppled longtime dictator Saddam Hussein ushering in a sectarian power-sharing system demonstrators says is corrupt and must be replaced.
Iraq is OPEC's second-largest producer but still lacks public services like reliable mains electricity or drinking water.
"We have one message: we don't want this government." said Ali, a demonstrator in Tahrir.
To address protesters' demands, the United Nations mission in Iraq (UNAMI) has proposed a phased programme of reforms.
It calls for an immediate end to violence, electoral reform and anti-corruption measures within two weeks and constitutional amendments and infrastructure laws within three months.
UNAMI chief Jeanine Hennis-Plasschaert has secured the support of Shiite spiritual leader Grand Ayatollah Ali Sistani and discussed the reform roadmap with members of parliament on Wednesday.
MPs have received a draft electoral reform bill but have yet to discuss it, and are planning to interrogate two ministers as part of a planned cabinet reshuffle.
Authorities must "step up to the plate and make things happen," Hennis-Plasschaert told AFP in an exclusive interview on Wednesday.
Piling on the pressure, the US this week "deplored the death toll" from protest-related violence and demanded authorities address demonstrators' "legitimate grievances".
Human Rights Watch said it had documented security forces shooting at medics, field clinics and ambulances with tear gas and live rounds during rallies.
"Medical workers should not have reason to fear for their lives as they engage in heroic work in already dangerous environments," regional director Sarah Leah Whitson said.
Doctors and activists have described to AFP a campaign of kidnappings they say is aimed at scaring them into stopping their work.
Late Wednesday, activist and medic Saba Mahdawi returned home after being held by unknown assailants for nearly two weeks, her family said.