At least 15 people were killed in clashes between Iraqi security forces and protesters in Baghdad's Sadr City district overnight as violence from a week-long nationwide uprising swept through the vast, poor swathe of the capital for the first time.
At least 110 people have been killed across Iraq and more than 6,000 wounded, with protesters demanding the removal of Prime Minister Adel Abdul Mahdi and a government they accuse of corruption.
The spread of the violence into Sadr City on Sunday night poses a new security challenge for authorities dealing with the worst violence in the country since the Islamic State group was defeated nearly two years ago.
Unrest is historically difficult to put down in Sadr City, a volatile district where about a third of Baghdad's 8 million people live in narrow alleys, many with little access to electricity, water and jobs.
The uprising over the past week has abruptly ended two years of relative calm unseen in Iraq since the fall of Saddam Hussein in 2003. Many Iraqis, especially young people, say entrenched government corruption means they received no benefit from returning stability after years of foreign occupation and sectarian civil war.
Critics say the government's fierce response to the protests has enflamed the public rage.
Reuters journalists have witnessed protesters being killed and wounded by snipers from the security forces firing into crowds from rooftoops though the interior ministry denies government forces have shot directly at protesters. The internet has been shut down across the country, leading to a communications vacuum that allows discontent to spread.
"The crackdown plus the internet blackout are angering people and it won't calm the situation," Jassim al-Hilfi, a lawmaker from the bloc of populist opposition cleric Moqtada al-Sadr who is boycotting parliament, told Reuters.
"People will not be silenced, and the politicians are not capable of meeting their demands."
President Barham Salih, whose role is normally above the day-to-day political fray, called on the armed forces to abide by rules of engagement and avoid using live ammunition.
"...Our armed forces which have protected the country and the people in the most serious confrontations with terrorism, are also capable of protecting citizens and their peaceful democratic practices in conditions of peace," Salih's office quoted him as saying.
"DOWNFALL OF THE REGIME"
Demonstrators have been calling for "the downfall of the regime", echoing demands in Arab Spring protests that swept across the Middle East in 2011. It is unclear how their demands could be met by the powerful Shi'ite religious parties that have dominated the country since Saddam's fall and show no sign of willingness to relinquish control.
Those parties control armed militia which gained influence in the war against Islamic State. They also have strong backing from Iran, creating a potential international dimension to the crisis in a country that is a client and ally of both Tehran and its biggest foe, Washington.
Iran's Supreme Leader, Ayatollah Ali Khamenei, tweeted on Monday: "#Iran and #Iraq are two nations whose hearts & souls are tied together... Enemies seek to sow discord but they've failed & their conspiracy won't be effective."
The military said early on Monday it was withdrawing from Sadr city and handing over to police in an apparent effort to reduce tension there.
A Sadr City resident reached by phone told Reuters later on Monday that the streets were again calm after a night of riots. Local militiamen were coming to inspect damage and police were deployed around the district's neighbourhoods.
The protests began spontaneously in Baghdad and southern cities, without public support from any major political faction in Iraq.
They have since spread to other areas, mainly populated by members of the Shi'ite majority. The unrest poses an unprecedented challenge for Abdul Mahdi, who took office last year as a consensus candidate of the Shi'ite parties.
U.S. Secretary of State Mike Pompeo told Abdul Mahdi in a phone call that he trusted the Iraqi forces and supported the Iraqi government in restoring security, a statement from the prime minister's office said.
Abdul Mahdi said life had returned to normal, according to the statement. The government has offered to spend more money on subsidized housing for the poor, stipends for the unemployed and training programs and loan initiatives for youth.
Iraqi authorities said they would hold to account members of the security forces who "acted wrongly" in the crackdown on protests, state TV reported.
The ministry also said authorities condemned all attacks against media outlets, after reports of raids at the offices of several local and international news outlets. Iraq's National Union of Journalists condemned the attacks, and the harassment and arrests of journalists covering the protests.
The protests precede Arbaeen, a Shi'ite pilgrimage when as many as 20 million worshippers trek on foot through southern Iraq in the world's biggest annual gathering, 10 times the size of the Mecca Hajj. Iran reopened a border crossing used by pilgrims which had been shut last week.