A bomb exploded near an Iraqi army patrol south of Baghdad on Wednesday, killing six soldiers, an officer and a hospital employee said.
The blast struck the patrol in the Jurf al-Sakhr area, where mortar rounds wounded 12 police on Tuesday.
It followed an attack by militants that killed 15 soldiers guarding an oil pipeline in northern Iraq.
Security force personnel have been frequently targeted by militants, as the government grapples with the worst unrest since 2008.
Iraqi authorities often tout operations targeting militants, but security forces have so far failed to quell the protracted surge in violence.
Foreign leaders have urged the Shiite-led government to do more to reach out to the disaffected Sunni Arab minority but Prime Minister Nuri al-Maliki has taken a hard line ahead of a general election scheduled for April.