Nearly 50 people have died in renewed anti-government protests across Iraq, officials said Saturday, with clashes breaking out as demonstrators turned their fury against the government and paramilitary offices.

The death toll from protests this month has climbed to 205, including dozens who were killed as they torched government buildings or offices belonging to factions of Hashed al-Shaabi force over the past two days.

The demonstrations first erupted on October 1, with protesters railing against government corruption and unemployment, while a second wave broke out late Thursday.

This latest round of demonstrations has been notably violent, with 48 people killed in as many hours.

Three protesters were killed in the capital Baghdad on Saturday, with medics and officials reporting trauma wounds sustained by tear gas canisters lobbed at demonstrators.

But the majority of victims have been in the Shiite-majority south, where protesters torched dozens of provincial government buildings, party offices and Hashed centres.

On Saturday, three people were shot dead while setting fire to a local official's home, a police source told AFP.

The previous night, 12 protesters died in Diwaniyah while setting fire to the headquarters of the powerful Badr organisation.

Top Hashed commanders have threatened "revenge" after their offices were attacked, and denounced those they said aimed at sowing "discord and chaos" in the country.

In a bid to contain the violence security forces have announced curfews across most of Iraq's southern provinces -- but brief protests nevertheless took place in Diwaniyah, Nasiriyah, Babylon and Najaf.

In the southern port city of Basra, protesters failed to come out in large numbers after security forces strictly enforced a curfew.

The Hashed was founded in 2014 to fight the Islamic State group but its factions have since been ordered to incorporate into the state security services.

"Public anger is directed at them in addition to governorate councils, for they were the obvious face of 'the regime'," wrote Harith Hasan, a senior fellow at the Carnegie Middle East Center.

But the attacks could also hint at political rivalries between the Hashed and populist cleric Moqtada al-Sadr, who has thrown his weight behind the demonstrations.

"The Sadrists, especially in their traditional strongholds such as Missan, saw this an opportunity to act against competing militias," such as Asaib Ahl al-Haq, Badr, and Kataeb Hezbollah, Hasan said on Twitter.

The United Nations on Saturday said it was "tragic" to see renewed violence but also warned against "armed spoilers".

"Armed entities sabotaging the peaceful demonstrations, eroding the government's credibility and ability to act, cannot be tolerated," said the UN top official in Iraq, Jeanine Hennis-Plasschaert.

Protesters gathered in Baghdad's emblematic Tahrir (Liberation) Square on Saturday morning despite efforts by riot police to clear them with tear gas.

"It's enough -- theft, looting, gangs, mafias, deep state, whatever. Get out! Let us see a (functioning) state," said one protester, referring to perceived cronyism and corruption in the country.

"We don't want anything, just let us live," he added as puffs of smoke from tear gas rose behind him.

Oil-rich Iraq is OPEC's second-highest producer -- but one in five people live below the poverty line and youth unemployment sits at 25 per cent, according to the World Bank.

About 60 per cent of Iraq's 40-million-strong population is under the age of 25.

The staggering rates of joblessness and allegations of corruption sparked the widespread protests on October 1 and the government has struggled to quell public anger by proposing reforms.

Prime Minister Adel Abdel Mahdi has suggested a laundry list of measures, including hiring drives, increased pensions and a cabinet reshuffle.

New education and health ministers were approved by parliament in a session earlier this month, the only time it was able to meet since protests began.

But a scheduled meeting of parliament on Saturday to discuss the renewed protests failed to take due to a lack of quorum.

Protesters so far have seemed unimpressed by the government's efforts.

"They told young people: 'go home, we'll give you pensions and come up with a solution'. They tricked us," said one of the rare woman protesters on Saturday, her young son at her side.

They have even directed some of their anger at Sadr and country's top Shiite religious authority, Grand Ayatollah Ali al-Sistani, who is deeply revered among most Iraqis,

"Sadr, Sistani -- this is a shame," a protester in Tahrir said on Saturday.

"We were hit! It's enough," he said, waving a tear gas canister fired earlier by security forces.