At least 47 other people were wounded in clashes with security forces.
Nasiriyah: Two Iraqi protesters were shot dead overnight in the southern city of Nasiriyah, where anti-government demonstrators shut down schools and blockaded bridges, a medical source told AFP Sunday.
At least 47 other people were wounded in clashes with security forces as protesters burned car tyres on roads and outside many public offices in the city, some 300 kilometres (200 miles) south of the capital Baghdad.
An estimated 350 people have been killed and thousands wounded in the protest movement that erupted on October 1 calling for a total overhaul of a government widely seen as corrupt and inefficient.
In Iraq's mostly rural south, schools and public offices have been severely affected with many students and teachers leading rallies and sit-ins outside public offices.
The education ministry has issued a directive that classes resume Sunday, the first day of the school and work week in Iraq. But protesters in Nasiriyah defied the ministry and shut down schools anyway, AFP's correspondent said.
In the oil-rich southern city of Basra, demonstrators blocked main roads just before dawn, including those leading to the ports of Umm Qasr and Khor al-Zubair.
The ports, which bring in food and medicine to Iraq but also export fuel products, have seen some delays in loading and offloading due to the unrest in recent weeks. Clashes also pitted protesters against security forces in Karbala, one of Iraq's two Shiite holy cities.