A suicide bomber blew himself up inside a Shia mosque in central Iraq, killing 10 people, amid nationwide violence that left 16 dead, including senior police and army officers.
The attack took place soon after evening prayers in Balad Ruz, 90km northeast of Baghdad, Muthana al-Timimi, head of Diyala provincial council's security committee, said.
Baladruz lies in Diyala province, which is home to Sunni and Shia Muslims and remains one of Iraq's most violent, even as the number of attacks nationwide has dropped off dramatically from its peak in 2006 and 2007.
The violence comes with just months to go before US troops must withdraw completely from the country, and as a series of US officials have passed through Baghdad this month to press Iraq to decide on whether it wants an extended US military presence.
Meanwhile, in the oil-rich, ethnically mixed province of Kirkuk, a car bomb targeting a passing convoy killed five people, including police Colonel Mohammed Mohsen and three other policemen.
The explosion occured in the town of Shahria, according to a police colonel there.
Khalaf al-Juburi, a doctor at the main hospital in the nearby town of Hawija, confirmed the death toll. Both sources said three policemen and three civilians were wounded.
Kirkuk is in the centre of disputed territory that is claimed by both the central government and Kurdish regional authorities. US officials have persistently said the unresolved row is one of the biggest threats to Iraq's future stability.
Also on Thursday, Brigadier General Mohammed Alaa Jassim was shot dead by gunmen while in his car on a busy thoroughfare in the Ghazaliyah neighbourhood of west Baghdad, an interior ministry official said.
Jassim was deputy commander of the air force's Al-Muthanna base in central Baghdad. His death was the fourth of a senior Iraqi official in the past week, with at least three others having narrowly escaped.
On Wednesday, a magnetic "sticky bomb" affixed to the car of Iraq's top theatre and film official detonated shortly after he parked it. Shafiq al-Mehdi's two bodyguards were wounded.
A day earlier, the deputy police chief of Kirkuk province in northern Iraq himself escaped an assassination attempt that involved four explosions which killed one other security force member and wounded 30 people.
Last week, a senior official in Iraq's foreign ministry, the head of Iraq's tax agency, and an army lieutenant colonel were killed by gunmen using silencers.
A police departmental chief was wounded in a separate incident involving the same weapon.
The Islamic State of Iraq, Al-Qaeda's front group in the country, posted a statement on the Internet jihadist forum Honein last week, claiming to have carried out 62 "operations" from the onset of March until April 5.