At least 25 killed in Iraq including bomb at Baghdad mosque

But attacks have continued to hit much of the country, with more than 4,000 people killed in violence already this year.

The worst of the violence struck the confessionally mixed north Baghdad neighbourhood of Waziriyah, where a bombing went off at a mosque at around 6:40 p.m. as worshippers were exiting following evening prayers.

At least 18 people were killed and 48 others were wounded, an interior ministry official and a medical source said, speaking on condition of anonymity.

No group immediately claimed responsibility for the attack against the Tamimi mosque, a Shiite Muslim place of worship, but Sunni militants linked to Al-Qaeda frequently set off attacks against Iraq's Shiite majority, who they regard as apostates.

Violence elsewhere in the country left seven people killed, including four in the restive northern province of Nineveh.

In three separate attacks in the province, which remains one of Iraq's least stable, gunmen killed three people, among them a school principal who was shot dead at his house.

And in provincial capital Mosul, a magnetic "sticky bomb" attached to a car killed another person.

Another sticky bomb killed one person in south Baghdad, and another died in a roadside bombing in a town on the capital's southern outskirts, while a gunman on a motorcycle killed a Sunni imam near the southern port city of Basra.

The surge in bloodshed has sparked concerns that Iraq is slipping back into the all-out sectarian war that plagued it in 2006 and 2007 and left tens of thousands dead.

Officials have vowed to press on with a campaign targeting militants they say has led to the capture of hundreds of fighters and the killing of dozens more, as well as the dismantling of militant training camps and bomb-making sites.