Two bombs exploded outside a mosque north of Baghdad where Sunnis and Shiites were jointly holding Friday prayers, killing nine people, official said, the latest in a spate of violence rocking Iraq.
Elsewhere on Friday, a shooting and and a bombing in northern Nineveh province left two people dead -- a soldier and a municipal official.
The surge in violence has left more than 4,000 people dead this year and sparked fears Iraq is slipping back into the brutal sectarian war that plagued it in 2006 and 2007.
The bombs were placed outside the Al-Salam mosque, a Sunni place of worship in the city of Baquba, at around midday as Sunnis and Shiites were streaming out of a joint prayer session, a police colonel said.
Nine people were killed and 31 others wounded, said Ahmed al-Azzawi, a doctor at the city's main hospital.
Baquba, which lies about 60 kilometres (35 miles) north of Baghdad, and the surrounding province of Diyala is mostly populated by Sunni Arabs, albeit with substantial Shiite Muslim and Kurdish minorities.
It remains one of Iraq's least stable areas, and is regularly struck by deadly attacks.
Three separate car bombs in and around the city killed 10 people on Tuesday.
Iraq has seen a spike in violence that has pushed unrest to its highest levels since 2008, when the country was emerging from brutal bloodshed that left tens of thousands dead.
Authorities have sought to tackle the attacks with wide-ranging operations targeting militants as well as tight traffic measures in the capital, but have faced criticism that the root causes of the violence are not being addressed.
Experts say militant groups are exploiting political infighting in Iraq and regional sectarian tensions fuelled by Syria's civil war to recruit and to carry out attacks.