The protests hit several provinces including Basra, despite Prime Minister Haider al-Abadi announcing fresh funds and pledges of investment for the oil-rich but neglected region.

The internet had been out of service across the country for 48 hours.

In the city of Basra, demonstrators tried to storm the governor's headquarters but were dispersed by police who fired tear gas at them, an AFP reporter said.

Police also fired tear gas at stone-throwing demonstrators who tried to push their way into the Zubeir oil field south of the city, the reporter said.

Several people, including journalists, were overcome by the gas, the reporter said.

In Nasiriyah, provincial capital of neighbouring Dhi Qar province, 15 demonstrators and 25 policemen were injured in clashes, deputy health director Abdel Hussein al-Jabri said.

The clashes, including hand-to-hand combat, erupted when the demonstrators gathered outside the governor's office and pelted security forces with stones.

In Muthana province bordering Basra, hundreds of demonstrators gathered outside the governor's headquarters and some torched parts of the building, a police source said.

Protesters in Muthana also set fire to the offices of the Iranian-backed Badr organisation in the province's largest city of Samawa.

On Saturday, protesters had set alight Badr's headquarters in Basra, prompting authorities to impose an overnight curfew across the whole province.

- Promises of investment -

In the Shiite shrine city of Najaf, security forces dispersed a large protest on Sunday morning, an AFP correspondent said.

A large contingent from Saraya al-Salam, a paramilitary force loyal to prominent Shiite cleric Moqtada Sadr who won May elections, also deployed in the streets.

Demonstrators also packed the streets of the holy central city of Karbala on Saturday night and clashed with police outside the offices of the governor.

An AFP reporter in the city said police fired into the air as demonstrators threw stones at them, adding that at least 30 people were wounded in the clashes.

The unrest first erupted last Sunday when security forces opened fire, killing one person, as youths demonstrated in Basra demanding jobs and accusing the government of failing to provide basic services including electricity.

Two more demonstrators died from gunshot wounds following protests overnight Friday, although it was not clear who killed them.

The protests -- which have spread north to Baghdad -- come as Iraq struggles to rebuild after three-year war against Islamic State group jihadists, which has ravaged their country's infrastructure.

Oil-rich Iraq has been rocked by a series of conflicts since the 1980s and says it needs $88 billion to rebuild after the war on IS.

Officially, 10.8 percent of Iraqis are jobless, while youth unemployment is twice as high, in a country where 60 percent of the population is aged under 24.

The oil sector accounts for 89 percent of the state budget and 99 percent of Iraq's export revenues, but only one percent of jobs, as the majority of posts are filled by foreigners.

On Saturday evening, the prime minister announced investment worth $3 billion (2.6 billion euros) for Basra province, as well as pledging additional spending on housing, schools and services.