Two US soldiers and an Afghan policeman were wounded in Tuesday evening's battle in the remote province of Nuristan which borders Pakistan, it said in a statement.

It said 30 insurgents had attacked a provincial reconstruction team base in Nuristan's Kamdesh district, and that coalition forces responded with small arms and mortar fire.

"Coalition soldiers killed 15 extremists," it said, adding that the base was undamaged.

The injured men were treated at the scene.

US military spokesman Colonel Tom Collins earlier told a press conference in Kabul that 12 militants were killed in the "significant" engagement.

Coalition forces also called in air support during the battle, he said.

Nuristan is one of the provinces where Taliban-led militants are most active. It is a wooded mountainous area where they find it easy to hide.

Separately, a civilian van was struck by a roadside bomb Wednesday in the Shahjoy district of southern Zabul province, police said.

One woman was killed and another woman and a child were injured. The wounded woman lost both legs, Zabul police chief Noor Mohammad Bakteen said.

Despite being toppled from power five years ago by the coalition, remnants of the Taliban regime have stepped up a deadly insurgency targeting foreign troops as well as the Afghan government.

The coalition is due to hand over control of operations in eastern Afghanistan to NAT0-led forces later this year. NATO assumed command in the troubled south last week.

Provincial reconstruction teams are civil-military programmes run by international forces that are intended to help with reconstruction and security in areas beyond the control of Kabul.

There are roughly 30,000 troops from around 30 countries in Afghanistan.

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