"A civilian around 20 years old was shot dead," a medical source in the city of Diwaniyah told AFP, as fresh rallies were held across southern Iraq against social and economic woes.

Shots were fired by a guard from the local headquarters of the Badr organisation, a powerful Iranian-backed armed group, where hundreds of people were protesting, the source said.

The latest death brings to nine the number of people killed in the protests, according to multiple sources, while authorities earlier this week said more than 260 security personnel have been wounded.

The unrest erupted in Basra province on July 8 when security forces opened fire, killing one person as protesters demanded jobs and basic services including electricity.

Others killed during the protests were shot by unknown assailants.

The Iraqi government swiftly denounced "vandals" it accused of infiltrating the protests.

The latest demonstrations saw thousands of people gathering across the south and also in the capital Baghdad, where a heavy security presence saw demonstrators dispersed by water canon and tear gas.

The crowds were broken up as they headed towards the fortified Green Zone, a high-security area of Baghdad where the government is headquartered.

In oil-rich Basra, people shouted slogans against the authorities as thousands gathered peacefully outside government headquarters.

Shouting "no to corruption", hundreds of people rallied in Nasiriyah, 160 kilometres (100 miles) northwest of Basra, chanting the anti-graft message which has characterised nearly two weeks of protests.

Demonstrators also surrounded the home of Nasiriyah's governor where security forces responded with tear gas.