At least two people were killed as protests escalated in the Iraqi capital Baghdad, with police firing tear gas to repel demonstrators.
The dead were reportedly hit by tear gas canisters. Scores were injured, including security forces.
Protests have erupted nationwide, with demonstrators marching on government buildings.
They are demanding more jobs, better public services and an end to corruption.
In the city of Nasiriya, protesters stormed a government building and set it alight, reports say.
Similar protests earlier this month were brutally put down by security forces, leaving nearly 150 people dead.
A government report has acknowledged that authorities used excessive force in quelling that unrest.
Ahead of the latest rallies, Iraq's leading Shia cleric, Grand Ayatollah Ali al-Sistani, used his weekly sermon on Friday to call for restraint.
Prime Minister Adel Abdul Mahdi warned on Thursday that although people could exercise their right to demonstrate, violence would not be tolerated.
Friday marks the first anniversary of Mr Mahdi taking office. He has promised a cabinet reshuffle and a package of reforms to address protesters' demands but many remain unconvinced.
What's the latest?
Hundreds of protesters gathered in Baghdad's Tahrir Square on Thursday evening and many camped out overnight.
Early on Friday they crossed a bridge, bringing them close to the Green Zone where government buildings and foreign embassies are located.
According to witnesses, security forces then fired a volley of tear gas to drive them back.
Ali Bayati, a member of the Iraqi Human Rights Commission, said two demonstrators had died after being hit in the head or face by tear gas canisters. He said nearly 100 people were injured. There was no corroboration for the figures and officials have not commented.
However, pictures from the scene did show at least one person, apparently hit by a canister, lying motionless on the street.
"We're not hungry, we want dignity," shouted one marcher quoted by AFP news agency.
Another said that Iraq's politicians had "monopolised all the resources".
Demonstrations were also reported in the southern cities of Diwaniyah, Najaf and Nasiriyah. In Nasiriyah, at least 3,000 protesters broke into a government building and set it alight, police said.
Meanwhile, in the southern city of Amara, six protesters were wounded when guards protecting the office of a Shia militia group opened fire, security sources told Reuters news agency.
Correspondents say confrontations could escalate later on Friday when supporters of Moqtada Sadr, another highly influential Shia cleric who leads the largest opposition bloc in parliament, are expected to take to the streets.
What's the background?
The protests started in Baghdad on 1 October. Most of those taking part were young and unemployed.
After security forces used live ammunition in an attempt to disperse Read More – Source