Three police and one civilian were killed as a roadside bomb struck a police vehicle in Kandahar, the former stronghold of Taliban militants in south Afghanistan on Tuesday.

"This afternoon, a roadside bomb hit a police van in Spin Boldak district killing four people including three police constables and a passerby,"commander of Border Police in the district General Abdul Razaq told Xinhua.

He blamed Taliban outfit for the attack, saying the insurgents by carrying out subversive activities want to destabilize the region.

Taliban militants fighting Afghan and the NATO-led troops have not made comment.