The killings come amid a surge in violence that has left more than 600 people dead this month, including several who were snatched from their homes.

More than 6,000 people have been killed this year, forcing Baghdad to appeal for international help in battling militancy just months before a general election, as official concern focuses on a resurgent Al-Qaeda emboldened by the war in neighboring Syria.

Violence on Friday struck in Baghdad and mostly in northern and western parts, with shootings and bombings targeting civilians, local officials, security forces and even a brothel.

But the most troubling of the bloodshed came early Friday morning, when authorities discovered the bodies of 18 men, including two tribal chiefs, four policemen and an army major, dumped in farmland near the town of Tarmiyah, just north of Baghdad.

All of them had been shot in the head and chest, police and a medical source said.

The kidnappers, wearing military uniform and travelling in what appeared to be army vehicles, abducted the men early Friday, telling their families the men were suspects in various cases and were being taken for questioning.

Their bodies were found hours later, the sources said.

There was another such incident in Salaheddin province, north of Baghdad. Seven men -- all maintenance workers and laborers at a local football field -- were found dead, their throats cut.

Three more corpses, all women, were also found in east Baghdad, their bodies bearing signs of torture. They were all shot in the head earlier on Friday, officials said.

Elsewhere in Iraq on Friday, attacks in and around Baghdad, and the cities of Mosul, Baquba and Kirkuk killed 23 people, officials said.

Among them were a bombing against a football pitch in west Baghdad that killed five, and a gun attack against a brothel in the capital's east that left six people dead.

NJF/NJF