Suspected Taliban militants shot dead five policemen and wounded three others in southern Afghanistan on Sunday, a hospital doctor said.

The policemen were attacked by four gunmen on two motorcycles in Charbagh, a southwestern residential neighborhood of Kandahar, said a doctor at the hospital where the victims were taken. He spoke on condition of anonymity because he was not authorized to talk to the media.

A purported Taliban spokesman, Qari Mohammed Youssef, telephoned The Associated Press to claim responsibility for the attack. The claim could not be verified by Afghan officials in Kandahar, a former Taliban stronghold, or in the capital, Kabul.

Earlier Sunday, an official said a Taliban rebel posing as a traveler shot dead four policemen as they slept at a remote checkpoint late Friday in the southern Helmand province.

The assailant asked the officers if he could spend the night with them because he was walking alone along a stretch of road in Helmand province, a hotbed of insurgency and the country's main poppy-growing region, said provincial administrator Ghulam Muhiddin.

After the officers went to bed, the man grabbed one of their rifles and shot four dead before a fifth woke and killed the assailant, Muhiddin said.

Also in Helmand, rebels attacked a civilian truck convoy after it had dropped off equipment Saturday at a U.S.-led coalition base, said Amanullah, a local police chief who uses only one name. The militants burned the trucks but freed the drivers.

Taliban insurgents have stepped up attacks on Afghanistan's fledgling police recently, and a series of ambushes in the neighboring provinces of Helmand and Kandahar has seen scores of officers killed.