Protesters, mostly unemployed youths, blame a political elite that has ruled Iraq since the toppling of Saddam Hussein in 2003, and demand a complete overhaul of the political system.

Iraqi security forces shot dead at least six anti-government protesters in Baghdad on Thursday and killed four others as they broke up a sit-in in the southern city of Basra, police and medical sources said.

Scores more were wounded in the clashes as weeks of deadly violence in Iraq over protests against an entrenched political elite showed no signs of abating.

Security forces used live fire against protesters near Shuhada Bridge in central Baghdad. Gunfire was used against demonstrators in Basra, the main source of Iraq's oil wealth, who had staged a days-long sit-in.

Elsewhere in southern Iraq, dozens of protesters burned tires and blocked the entrance to the port of Umm Qasr, preventing lorries from transporting food imports, just hours after operations had resumed, port officials said.

A crackdown by authorities against mostly unarmed protesters has killed more than 260 people since demonstrations began on Oct. 1 over lack of jobs, chronic power and clean water shortages, poor education and healthcare and corruption.

The internet returned briefly in most parts of Iraq on Thursday but went out again after 1:00 p.m. local time. Internet outages have been imposed by the government to try to stem unrest.

The government says it is enacting reforms but has offered nothing that is likely to satisfy most protesters.

Stipends for the poor, more job opportunities for graduates and pledges to punish a handful of corrupt officials have come too late for those demanding an overhaul of state institutions, a flawed electoral process and system of governance that has fueled endemic corruption, many Iraqis say.

Protesters have stopped fuel tankers entering or leaving on Wednesday at the Nassiriya oil refinery, but oil and security officials said operations resumed on Thursday. Oil production and exports have not been significantly affected by the unrest, oil ministry officials say.

But the halting of fuel tankers that transport fuel from the Nassiriya refinery to regional gas stations caused fuel shortages across the southern Iraqi province of Dhi Qar. The refinery had recently been producing around half its capacity, oil officials said.