Taliban militants killed 31 passengers travelling in a bus from Kandahar to Kabul in Afghanistan, the country''s Defense Ministry said on Sunday.

According to the ministry, the tragedy occurred on Friday in the southern province of Kandahar when the militants surrounded the bus and slaughtered the passengers, accusing them of collaborating with the central government.

The bodies were only found on Sunday, the ministry said.

Southern Afghanistan is the stronghold of radical Taliban movement ousted by the U.S.-led coalition from government in the 2001 campaign. Taliban have stepped up attacks on Afghan and foreign troops this year.