A suicide bomber blew himself up in a Shiite mosque north of Baghdad on Saturday, the deadliest in a series of attacks that left 24 people dead nationwide days ahead of Shiite commemorations.
The unrest is the latest in a surge in nationwide violence which comes as the country grapples with months of protests by its Sunni Arab minority, tensions in a swathe of territory that Kurdish leaders want to incorporate into their autonomous region in the north and protracted political deadlock in Baghdad.
Saturday's deadliest attack struck Taji, a predominantly Sunni town that lies just north of Baghdad.
A suicide bomber blew himself up inside the Al-Rahman mosque in the town at about 8:00 pm (1700 GMT), according to an interior ministry official and a medical source.
At least 15 people were killed and 31 others wounded in the explosion, the officials said.
The mosque is frequented by Shiite Muslims and lies in a Shiite area of Taji.
No group immediately claimed responsibility for the attack, but Sunni militants linked to Al-Qaeda often carry out suicide attacks and frequently target Iraq's Shiite Muslim majority population, whom they regard as apostates, especially during times of commemorations.
The bombing comes just days before Shabaniyah ceremonies, which mark the birth of Imam Mehdi, Shiite Islam's so-called 12th imam. The commemorations are due to take place in the holy Shiite shrine city of Karbala on Monday.
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Elsewhere in Iraq on Saturday, a suicide car bomb and two separate shootings killed nine.
In the main northern city of Mosul, a suicide attacker set off a vehicle rigged with explosives near a police patrol on the city's southern outskirts.
The explosion killed four people including a policeman, police and medical officials said.
And in the ethnically mixed town of Tuz Khurmatu, which lies at the heart of the area disputed between the Kurds and Baghdad, gunmen opened fire on patrolling police, killing three and wounding a fourth, security and medical officials said.
The tract of land, which the Kurds want to incorporate over the objections of Baghdad, stretches from Iraq's eastern border with Iran to its western frontier with Syria.
Diplomats and officials say the unresolved row is one of the biggest threats to Iraq's long-term stability.
And in the mostly Sunni Arab city of Tikrit, militants fired on day labourers waiting near a grain silo, killing two and wounding four, officials said.
Iraq has suffered an upsurge in violence since the beginning of the year, coinciding with rising discontent among Sunnis that erupted into protests in late December.
Analysts say a failure by the Shiite-led authorities to address the underlying causes of the demonstrations has given militant groups both a recruitment platform and room to manoeuvre.