The policemen were travelling in the volatile Zhari district, about 30 kilometres (20 miles) west of Kandahar, when they were attacked, the provincial police chief Sayed Aga Saqeb told AFP.

"Seven police were killed and the police vehicle completely destroyed," he said. "This mine was detonated by remote control."

Kandahar province is the birthplace of the Taliban movement that is waging an insurgency against the government and its foreign allies. The rebels regularly use suicide and roadside bombings in their campaign.

Police are the most often attacked of the security forces in Afghanistan, with several hundred killed in attacks this year.