An Afghan official says that one policeman was killed and three were wounded when their vehicle hit a roadside bomb in central Uruzgan province.

The province's deputy police chief, Mohammad Aslam Kochia, says the bomb exploded when the police vehicle drove over it in Tarin Kot, the provincial capital, on Thursday afternoon.

Afghanistan is one of the most heavily mined countries in the world, and roadside bombs exact a heavy toll on the population. The United Nations says that 10,000 Afghan civilians were killed or wounded, mostly by insurgent attacks, in 2014.

Police are also dying in unprecedented numbers as they come under attack from the Taliban-led insurgents who have been testing the Afghan security forces since they took the lead in the war around 18 months ago.