Iraqi security forces have found the bullet-riddled bodies of 53 men in a mainly Shia area south of Baghdad.
The men, who were bound, blindfolded and had wounds to the head or chest, were found in a field outside Hamza al-Gharbi, a town in Babil province.
It was not immediately clear who the victims were or why they were killed.
Meanwhile, Prime Minister Nouri Maliki alleged that Kurdish-controlled Irbil province is becoming a haven for the jihadist-led Sunni rebels.
However, he provided no evidence to back up the claim, which was vigorously denied by a Kurdish official in London.
The prime minister's relationship with the autonomous Kurdistan Regional Government, which controls Irbil and two other neighbouring provinces, has deteriorated as the Islamic State in Iraq and the Levant (Isis) and its allies have taken control of large swathes of northern and western Iraq.
Security officials said an investigation was under way to determine the identities of the bodies discovered in an agricultural area near Hamza al-Gharbi early on Wednesday, as well as the circumstances of their killings.
The victims were men aged between 25 and 40, police and mortuary officials said. It appeared they were killed several days ago.
The area south of Hilla is predominantly Shia and has not seen any significant activity by the jihadist Islamic State in Iraq and the Levant (Isis) and its allies over the past month.
However, Sunni militants have been carrying out attacks around the southern outskirts of Baghdad since the spring. In response, Shia militiamen have been rounding up Sunnis they suspect of being behind the violence, many of whom later turn up dead.
The number of bodies found around the capital has reportedly risen since the beginning of the year, sparking fears of a return to the peak of the sectarian civil war in 2006 and 2007, when dozens were found each day dumped by the roadsides and in fields and canals.
Elsewhere in Babil province on Wednesday, two car bombs reportedly killed two people and wounded 13 others.
At least eight soldiers were killed and 30 injured in fighting with jihadists at a military base in the Mansouriya area, north of the city of Baquba in Diyala province, a medical official told the AFP news agency.
'Battle of destiny'
In his weekly televised address, Mr Maliki said government forces were fighting a "battle of destiny" to protect Iraq, its territorial integrity and sovereignty from internal and external threats.
He stressed that Iraq was facing a "conspiracy" by jihadist militants and remnants of the Baathist regime of former President Saddam Hussein, who he said were operating out of Kurdish areas.
"We will never be silent about Irbil being a headquarters for the terrorist operations of [the Islamic State in Iraq and the Levant], and Baathists and al-Qaeda," he warned.
"They will lose, and their host will lose also because he did not provide an example of patriotic partnership."
The president of the Kurdistan Region, Massoud Barzani, has said he no longer feels bound by the Iraqi constitution and intends to hold a referendum on independence within months. He has also insisted that Kurdish parties will not join another Maliki-led government.
Kurdish Peshmerga fighters have meanwhile moved into previously disputed areas that have been abandoned by Iraqi security forces in the face of Isis's advance, such as the oil-rich region of Kirkuk.
Reproduced under licence from BBC News © 2014 BBC