Pakistan has described as cowardly an air and artillery attack by US forces that killed 11 Pakistani soldiers near the Afghan border yesterday.

The US has admitted carrying out the attack but insisted that its forces were retaliating after a hostile act by pro-Taliban militants in the area.

Pakistan described the action as a gross violation of the international border and said it undermined the basis of the country's co-operation with coalition forces.

The sequence of events is still the subject of dispute.

The US military says its forces came under small arms fire and grenade attacks about 200 metres inside Afghanistan's eastern Kunar province.

The troops responded by launching an air and artillery strike on the area just inside Pakistan where they believed the attack was launched.

The US insists Pakistani forces, also in the vicinity, were informed about the action.

But Pakistan's Prime Minister Yousuf Raza Gilani vehemently condemned the strike, which has fuelled tension between Pakistan and the US over the issue of militants ranging across the Afghanistan-Pakistan border areas.