Taliban militants have beheaded four men for allegedly spying for the government in southern Afghanistan, an official said.

The bodies of the men were discovered in Washer district of volatile Helmand province late on Sunday.

"The four men were civilians who were beheaded by Taliban for allegedly spying for government," provincial spokesman Daud Ahmadi told AFP.

The Taliban had found satellite phones in the men's possession and thought they were spies, he said, adding that mobile phones do not work in that district and it is normal for people to use satellite phones.

The militants, who have in the past used beheading as a punishment on alleged spies and traitors, were not immediately available for comment.

The Taliban have waged a 10-year insurgency since their hardline Islamist government was toppled by a US-led invasion in the wake of the Al-Qaeda attacks on New York and Washington in 2001.

Around 130,000 US-led troops are fighting the Taliban alongside the government forces of President Hamid Karzai.