Two boys have been found beheaded in a restive rural part of southern Afghanistan.

The boys, who were 11 and 16, were killed when they passed through a Taliban-controlled area on the way to a nearby shrine, the governor of their home district of Zhari told the Guardian.

"We don't know the reason for that," Jamal Agha said in a phone interview from Kandahar. "They were very young, they were not of an age to be soldiers."

He gave their names as Khan and Abdul Wahab, but said he had no contact details for their families.

The provincial governor's spokesman, who first announced the killings, said the boys had been denounced as spies after accepting food handouts from local police.

The district police chief refused to comment on whether he knew the boys, saying he needed permission from provincial authorities to speak to the media. It was unusual secrecy for a country where security officials are remarkably accessible to journalists.

Agha said he had spoken to people in the area where the boys were found dead, and they had blamed the Taliban.

But a spokesman for the insurgent group condemned the murders and denied any role in them. The Taliban in the past have rejected brutal killings that analysts believe they carried out, but the inconsistencies between stories given by government officials also cast doubts on their account.

Thousands of Afghanistan's civilians have died in over a decade of war since the overthrow of the Taliban, many of them killed by homemade bombs or Nato air strikes that missed their intended targets or also took out innocent bystanders.

The United Nations said more than 2,700 civilians died in the country last year, the vast majority of them killed by insurgent bombs or targeted killings, although government and Nato forces also caused over 300 deaths.

Additional reporting by Mokhtar Amiri