An Afghan official says the Taliban have attacked security positions northwest of Kabul, killing at least five police.

Mohammed Zaman, the provincial police chief for Ghazni province, says the attack late on Saturday set off a two-hour gunbattle.

The Taliban have stepped up attacks across Afghanistan since the United States and Nato formally concluded their combat mission at the end of 2014.

In the western Ghor province, meanwhile, a roadside bomb killed a young shepherd and wounded five others.

Police Spokesman Iqbal Nizami says the Taliban planted the bomb in order to target security forces.

In the eastern Khost province, Police Spokesman Basir Bina says a roadside bomb killed two children and wounded another nine. Both bombs went off on Saturday.