BAGHDAD (AP) — Iraq faced the prospect of a deepening political crisis Saturday, after four days of unrest left at least 64 people dead, and authorities lifted a round-the-clock curfew in the capital meant to quell the anti-government demonstrations.

The unrest is the most serious challenge for Iraq since the defeat of the Islamic State group two years ago.

Security forces opened fire directly at hundreds of protesters in central Baghdad Friday, despite calls from Iraq's top Shiite cleric for both sides to end four days of violence "before it's too late."

It turned out to be the deadliest day of violence in the capital, with 22 protesters killed, Iraqi officials said Saturday. Health and security officials said 183 were injured in the protests, adding that most of the injuries were to the head and chest.

According to officials, that raised the national death toll to at least 64 people killed since the demonstrations erupted in the capital and the south's major cities on Tuesday.

On Saturday, security remained heavily deployed in Baghdad. Streets and main squares were open to traffic after curfew was lifted at 5 a.m. local time, though access to the Green Zone, the area housing government offices and foreign embassies, was restricted. Municipal workers were clearing the streets of the bullets and debris left behind by the latest confrontations.

Abu Muslim, a taxi driver in Baghdad, praised the lifting of the curfew.

"It is a good move for the sake of our families. We are now able to go on the streets. I have been on the street since 5 a.m., nothing is going on today," he said.

Parliament is to convene for an emergency session later in the day to discuss protesters' demands. Both Prime Minister Adel Abdul-Mahdi and Parliament Speaker Mohammed al-Halbusi called on protest representatives to meet to hear their demands.

But with a call from the largest bloc in parliament to boycott the session, it was not clear if a session would take place.

Curfew remained in place in other southern cities, where violence has been deadly and where there are concerns more rallies were organized.

Spontaneous rallies started as mostly young demonstrators took to the streets demanding jobs, improved services like electricity and water, and an end to corruption in the oil-rich country.

In a desperate attempt to curb the growing rallies, authorities blocked the internet and imposed an around-the-clock curfew in the capital.

But the protesters, many of whom camped on the streets, continued to turn up in Baghdad and a number of southern cities, including Nasiriyah, Amarah, and Kut.

On Friday, influential Shiite cleric Muqtada al-Sadr has called on Abdul-Mahdi's government to resign and hold early elections, saying in a statement that the shedding of blood of "Iraqis cannot be ignored." Al-Sadr, who controls the largest bloc in parliament, also called on members of his coalition to boycott sessions until the government puts forth a program acceptable to the people.

Abdul-Mahdi said in an address to the nation that the protesters' "legitimate demands" had been heard, adding that the security measures used against the demonstrations were like "bitter medicine" that needs to be swallowed.