A women wearing an explosives belt has blown herself up near a Shia mosque in Diyala province north of Baghdad, killing 11 others, Iraqi police say.
Victims were taken to Baghdad because of safety fears in Baquba
The attack took place in the town of Khan Bani Saad, south of Baquba, capital of the restive province.
Eighteen people were wounded in the attack, near a popular market in the town, a local military commander said.
Reports say victims were treated in Baghdad, rather than the mainly-Sunni Baquba because of security concerns.
BBC Baghdad correspondent Jonny Dymond said the bombing looks very much like a religiously motivated attack.
The bombing is the third reported to have been carried out by female attacker in the past two months in the Baquba area.
Diyala has defied the trend towards lower violence in Baghdad and much of central Iraq over the past six months.
Diyala is the current battleground between the Sunni insurgency and its opponents and also one of the places in Iraq where Shia and Sunni live side by side, our correspondent says.
The area around the mosque was crowded with people in the run up to the important Shia ceremony of Ashura which falls on Saturday.
In other violence, two civilians were reported killed and 10 wounded when a roadside bomb targeting an Iraqi army patrol exploded in central Baghdad, police said.
The bodies of another six people were found in different areas of Baghdad on Tuesday, police said.
There were also reports of two people dying in roadside bombings in Nahrawan, south of Baghdad, and three similar attacks in quick succession in central Baghdad that wounded three people.
On Tuesday, US secretary of state Condoleezza Rice made an unannounced visit to Iraq during which she praised the progress made in Iraq, nearly five years after the US-led invasion which overthrew Saddam Hussein.