Nato-led troops killed up to 150 insurgents in a ground and air operation in southeastern Afghanistan, the alliance said today.
The latest fighting, the biggest clash in Afghanistan in months, was last night in the Bermal district of Paktika province, bordering Pakistan, Nato said.
"Two large groups of insurgents were observed infiltrating Paktika province from Pakistan," Nato said. It did not say if there were any casualties among Nato or Afghan government troops.
Afghan anger over the infiltration of Taliban militants from Pakistan has seriously soured relations between the neighbours, both important US allies in the war on terrorism.
Last year was the bloodiest since US-led forces overthrew the Taliban in 2001. More than 4,000 people, including nearly 170 foreign troops, were killed.
Most of the violence has been in southern and eastern areas bordering Pakistan. The Afghan government says the militants have sanctuaries in Pakistan from where they launch attacks across the border.
Pakistan was the main supporter of the Taliban until the September 11 attacks on the United States. It denies any official help for the Taliban but says some militants are crossing into Afghanistan from Pakistani tribal lands where Pakistani forces have been battling militants.