DIWANIYAH, Iraq — Three young boys were killed and another was badly wounded on Sunday when an unexploded cluster bomb detonated in south Iraq, medical and security officials said.

The children, who officials estimated were aged between six and 12, were playing in a garden in the village of Al-Attah, just east of the southern city of Diwaniyah, when the bomb exploded at about 2:00 pm (1100 GMT).

"Diwaniyah hospital received the bodies of three children killed by an old cluster bomb, and one other was seriously wounded," said Ahmed al-Bideri, spokesman for the provincial health department.

A police official, who declined to be named, confirmed the toll and also attributed the explosion to a cluster bomb.

Iraq last year asked for international help to clear an estimated 20 million unexploded land mines and ordnance that are a legacy of the 1980-1988 war with Iran, the 1990 assault on Kuwait and the 2003 US-led invasion.

A United Nations official said last year that Iraq was one of the most affected countries in the world when it came to land mines and unexploded ordnance.

Since 1991, an estimated 8,000 Iraqis, among them 2,000 children, have been killed or maimed by mines and cluster bombs, according to United Nations figures.

US forces passed through Al-Attah during the 2003 invasion that ousted Saddam Hussein, and it was also one of the sites of a Shiite uprising against Saddam's regime in 1991 that was ruthlessly suppressed by the ex-dictator.