BAGHDAD, Iraq (AP) -- Iraqi security forces have detained an al-Qaeda militant suspected of planning an attack targeting the World Cup in South Africa next month, an official said yesterday.

Maj Gen Qassim al-Moussawi, a spokesman for Baghdad security services, said Abdullah Azam Saleh al-Qahtani was an officer in the Saudi army. He is suspected of planning a "terrorist act" in South Africa during the World Cup beginning June 11, al-Moussawi told a news conference in Baghdad.

He said al-Qahtani entered Iraq in 2004 and is suspected in several attacks in the capital and elsewhere in the country.

Yesterday, assailants disguised in Iraqi military uniforms beheaded a Sunni cleric and stuck his head on an electricity pole in the town where he preached against al-Qaeda, the cleric's son and Iraqi police said.

The son of the cleric Abdullah Jassim Shakour told The Associated Press the gunmen wearing military uniforms came to the family house in the town of Sadiyah north of Baghdad, took his father into a room, killed him and walked away with his head.

The family found the headless body in the house, said the son, Mohammed. When they went to report the killing to the police, they saw his head on an electric pole in the centre of the town.

"I was sleeping and screams from the street woke me up," said one of the victim's neighbours. "When I stepped out of my house, I saw the head of the cleric on the top of the pole."

The neighbour spoke to The Associated Press on condition of anonymity out of fear of the militants. He also said the cleric was known for speaking against al-Qaeda and called on worshippers to fight the militant group during last Friday's prayer.

A police official confirmed that four gunmen stormed the house in the morning and beheaded him. He spoke on condition of anonymity because he was not authorised to speak to the media.

Insurgents have often used Iraqi uniforms to disguise themselves during attacks. The uniforms are widely available in Iraq.

Violence in Iraq has fallen dramatically over the past few years, though Sunnis who have revolted against al-Qaeda in Iraq or are perceived as co-operating with the Shiite-led government are often targeted.