A 12-year-old girl and a 15-year-old boy have been killed in an acid attack in Afghanistan, an official said Saturday, with witnesses claiming it was because of their friendship in what is an ultra-conservative country.

The bodies were discovered on Friday in wasteland in the Esfandi area of Ghazni province in south central Afghanistan, provincial police chief Zorawar Zahid told AFP.

"Their bodies and faces were burnt by acid," he said.

The police chief said officers were investigating the motive for the attack, but witnesses who found the bodies told AFP the two were probably killed because of their friendship.

No one has claimed the bodies, which are still in Ghazni hospital, police said.

The attack is the latest incident to highlight the dangers still faced by many young men and women in Afghanistan 10 years after a US-led invasion ousted the Taliban, notorious for their oppressive policies against women and conservative attitude towards relationships.

On December last year, a 17-year-old Afghan girl and her family were sprayed with acid, apparently after rejecting a marriage proposal. The girl, Mumtaz, was seriously injured when several masked gunmen broke into her home in the northern city of Kunduz and sprayed acid in her face.