Police have discovered the bodies of 18 men who were abducted from their homes and shot in the head in a town near Baghdad, the deadliest this year in a spate of execution-style killings across Iraq.

The victims were taken from their homes early on Friday by men wearing military uniforms, police sources said. Two of the abductors were dressed as army officers.

"It is definitely al-Qaeda because this is the area where they are operating," a senior official in Iraq's federal police told the Reuters news agency, declining to be named. The victims may have been chosen because they were seen as supportive of Iraq's Shia-led government, the source added.

The corpses were found grouped together in an orchard in Meshahda, a predominantly Sunni Muslim area around 32 km north of the Iraqi capital.

Such killings are on the rise in Iraq, alongside a growing insurgent campaign of bombings and gun attacks targeting security forces and civilians.

Abductors dressed as soldiers have often carried out such killings in this area north of the capital.

Although al-Qaeda-linked armed groups in Iraq mainly carry out attacks on Shia, they also target fellow Sunnis through kidnappings, killings and extortions.

Security officials, government employees from both sects and government-backed Sunni Sahwa armed group members are all seen as prime targets for al-Qaeda.

'Silent operations'

The goal of such attacks "is to weaken the relationship between the people and the security forces," Ali al-Haidari, an Iraqi security expert, told Reuters.

He said Iraqi authorities refer to such incidents as "silent operations" because they are not aimed at controlling land or confronting security forces head on.

This year has been Iraq's most violent since 2006-7, when tens of thousands of people died at the height of sectarian strife between Sunnis and Shia.

On Wednesday, police found the bodies of 13 people around Baghdad, the apparent victims of execution-style shootings. It did not appear that Friday's killings were linked to those earlier in the week.

Among those killed on Friday were a police officer and an army official, the headmaster of a school and a mayor from the neighbourhood. The victims also included a Sunni tribal sheikh and his son.

Source: Agencies