A bombing against a Shiite mosque as worshippers were streaming out was the deadliest of attacks across Iraq that left 35 dead on Wednesday, part of a surge in violence.
Authorities have sought to tackle the country's worst bloodshed since 2008 with a variety of measures ranging from massive security operations targeting militants to implementing tight restrictions on vehicle movement in the capital in a bid to stemming the number of car bombs.
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 Wednesday's violence struck the confessionally mixed north Baghdad neighbourhood of Waziriyah, where a bombing went off at a mosque at around 6:40 pm (1540 GMT) 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.
But the government has faced criticism for not doing more to defuse anger in the Sunni Arab community over alleged ill-treatment at the hands of the Shiite-led authorities, which analysts and diplomats say militant groups exploit on the ground to recruit and carry out attacks.
This month, an Al-Qaeda front group claimed responsibility for a spate of car bombs in Baghdad that targeted Shiite neighbourhoods and left 50 dead, and have explicitly said attacks have been carried out in retribution for operations targeting Sunnis and executions of convicted militants.
At least 35 killed in Baghdad mosque bombing