Gunmen shot dead 16 members of the same Shia family before blowing up their two neighbouring homes south of the Iraqi capital overnight, police and medics said.
The attack took place in the town of Latifiya, 40 km (25 miles) south of Baghdad. The dead included six children and eight women.
“Gunmen broke into our house overnight and shot my father four times in the head, they killed my two brothers, they killed my cousin, they were shooting everyone they saw, I escaped from the back door,” said Haneen Mudhhir, crying in hospital.
It was not immediately clear who carried out the attack but Sunni Islamist militants, including an al-Qaeda affiliate, have been striking with a ferocity not seen in years.
More than two years of civil war in neighbouring Syria have aggravated deep-rooted sectarian divisions in Iraq, fraying an uneasy government coalition of Shia, Sunni and ethnic Kurdish factions.
Separately, a suicide bomber attacked a police headquarters in the northern city of Mosul, killing five policemen early on Wednesday. A roadside bomb also struck a patrol in Tarmiya, north of Baghdad, killing five soldiers.
About 800 Iraqis were killed in August, according to the United Nations, with more than a third of the deadly attacks happening in Baghdad.
The bloodshed, 18 months after US troops withdrew from Iraq, has stirred concerns about a return to the sectarian slaughter of 2006-07, when the monthly death toll sometimes topped 3,000.
Reuters