The bloodshed, coupled with a protracted standoff between security forces and anti-government forces in Anbar province west of Baghdad, has left nearly 800 people dead so far this month and comes with elections looming in April.
The mortar fire struck Jaizan, a predominantly Shia village just north of the confessionally-mixed city of Baquba, killing six people and wounding two others, security and medical officials said.
Among the fatalities were two women and a young boy.
Baquba is the capital of Diyala province, which remains one of Iraq's least stable and is regularly the site of violent attacks.
Iraq has grappled with an extended spike in violence, with nearly 800 people killed so far this month, according to an AFP tally, more than three times the toll for January 2013.
Diplomats and foreign leaders, including US President Barack Obama, have urged Baghdad to pursue political reconciliation with the disaffected Sunni minority to undercut support for militancy, but with polls due on April 30, Prime Minister Nuri al-Maliki has taken a hard line.
While the Shia-led government has offered some concessions, it has mostly focused on wide-ranging security operations targeting militants.
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