The shooting, which is the latest in a series by Afghan security personnel targeting their local and foreign colleagues, occurred in Gereshk district of volatile Helmand province on Thursday.

"A cook and a policeman first food-poisoned their colleagues in their post, and after they fell unconscious they were shot dead," provincial spokesman Ahmad Zeerak told AFP.

He said the policeman involved in the shooting had been arrested but the cook was still at large.

Farid Ahmad Farhang, a provincial police spokesman, confirmed the incident.

The Taliban claimed responsibility for the attack, according to purported spokesman Yousif Ahmadi, who said eight policemen were killed and their weapons seized.

Afghan police are the key force in supporting US-led NATO forces in a war against the Taliban militants.