Car bombs have exploded in predominantly Shi'ite areas of central and southern Iraq, killing at least 18 people and wounding more than 50 others.
Two of the blasts Monday happened in Amarah, 300 kilometers southeast of Baghdad. Officials say those bombings killed at least nine people.
Deadly bombings also hit Diwaniyah, Karbala and Mahmoudiya.
Iraq has seen a surge in violence in the past week that has left at least 180 people dead.
It began last Tuesday when government troops raided a Sunni protest site in the central town of Hawija. Clashes there left 53 people dead and were followed by unrest in western and northern Iraq.
Iraqi Prime Minister Nouri al-Maliki has appealed for calm and dialogue, urging Iraqis in a televised address Thursday "not to remain silent" about what he called efforts by terrorists to drag the country back toward a sectarian civil war.
The violence is the deadliest in four months of protests by Iraq's minority Sunnis, who have been demanding Mr. Maliki's resignation.
They accuse his Shi'ite-led government of marginalizing the Sunni community and unfairly targeting its leaders for prosecution and arrest.