A car bomb has killed 25 people and injured about 60 at a Shia mosque in a town close to the Iraq city of Baquba.
Wednesday saw bomb attacks across Iraq such as this in Khalis
The bomb went off just after dark as worshippers filled a busy market street in Howaider, 36 miles (60km) north-east of the capital Baghdad.
Other attacks in Iraq on Wednesday left at least 17 people dead.
Iraq's politicians have failed to make any progress on forming a new government. They are now due to hold a session of parliament next Monday.
The country has been hit by a wave of violence between Iraq's two main Muslim branches, the Sunni and Shia, which was sparked by the destruction of a Shia shrine in Samarra in February.
A triple suicide bombing at a Shia mosque in Baghdad killed at least 90 people on Friday.
The attack in Howaider came just before 2100 local time (1700 GMT).
"The car full of explosives was parked close to the mosque and those killed were worshippers who were leaving the sanctuary after evening prayers," a defence ministry official said.
Some passers-by in the market were also caught in the blast, police spokesman Lt Col Falah al-Mohammedawi told the Associated Press.
Some of the casualties were taken to a nearby US base for treatment.
The BBC's Andrew North in Baghdad says it is not yet clear if the mosque had been the target.
But the US and Iraqi authorities increasingly see such attacks as attempts to stir up sectarian tensions, he says.
Howaider and the surrounding area, with its mix of both Shia and Sunni communities, have been the scene of frequent tensions. A car bomb killed 30 in the town last October.
In other violence in Iraq on Wednesday:
Iraqi security forces came under attack across Iraq
- Gunmen killed three members of the Iraqi security forces in the Mosul area
- Two Iraqi army soldiers are shot dead near the northern oil refinery town of Baiji
- Gunmen killed two lorry drivers are kcarrying goods for the US military on a road between Ramadi and Rutba
- A car bomb killed at least two people at a market in Tal Afar
- Two policemen and a civilian were killed when a roadside bomb hit a police patrol in central Baghdad
- Two US soldiers were killed by a bomb just south of the city and a third died in a separate attack in Baghdad
- A bomb at a market in the town of Khalis killed two civilians and wounded at least 20