Four children have been killed and one wounded in southern Afghanistan when unexploded weaponry they were playing with blew up, an official said Saturday.

The children aged between six and ten found the "unexploded ordnance" in Pajwayi district of volatile Kandahar province on Friday and brought it home, provincial spokesman Jawed Faisal told AFP.

"They were playing with the unexploded ordnance at home when it exploded, killing four of them" he said, adding the injured child was taken to hospital and was in good condition.

Blasts caused by unexploded weaponry left in Afghanistan from three decades of war have caused the deaths and injuries of many children and adults in the country.

According to a recent UN report, child casualties from Afghan conflicts rose by over a quarter last year with an average of nearly five children killed or injured every day in 2011.

Tens of thousands of Afghan children are forced by poverty to work on the streets and collect metal scraps to sell and support their families. They often fall prey to Taliban bombings, as well as other violence and abuse.