Basra police said at least nine people were killed and 37 others wounded when two car bombs exploded Monday in two neighborhoods, CNN reported.
In Haditha, gunmen ambushed two police checkpoints, killing eight officers, police said.
Seven car bombs in Baghdad on Monday killed seven people and wounded at least 42 others, police said. Five of the bombs were detonated in predominantly Shiite neighborhoods, officers said.
Officials said the bodies of eight civilians kidnapped west of Ramadi Saturday were found late Sunday, CNN reported. All eight were shot to death.
Earlier, the bodies of six police officers, also abducted Saturday, were found near Ramadi, CNN said.
Tensions between Iraq's Sunnis and Shiites have heightened in recent months, with violence alternating between attacks against Sunnis and attacks against Shiites.
In a statement Sunday, Iraqi Prime Minister Nouri al-Maliki urged clerics to reject sectarianism and promote unity.
"Those who are targeting mosques and other locations are the enemies of Sunnis and [Shiites]," Maliki said. "They are plotting to ignite sectarian strife as they have tried before."