KABUL (AFP) - Seven schoolchildren were killed and three wounded by a roadside bomb in south-eastern Afghanistan on Monday, an official said.

The bomb was planted on the side of a main road in the Khairkot district of Paktika province, and exploded when the children stepped on it while playing.

"This afternoon as a result of the mine explosion in Khairkot, seven children from one family lost their lives," provincial spokesman Mokhlis Afghan told AFP.

He said they were aged 7-12 and were in elementary school. The injured children were taken to hospital.

No one has claimed responsibility for the incident, but roadside bombs are the Taleban's weapon of choice in their 12-year war against US-led and Afghan security forces.