Air and ground assaults by NATO-led and Afghan forces killed up to 150 rebels who infiltrated Afghanistan from Pakistan overnight, the Afghan and NATO military said on Thursday.
The men were seen gathering on the Pakistan side of the border and crossing into the eastern province of Paktika in two large groups, NATO's International Security Assistance Force said.
They were "monitored, tracked and subsequently engaged in Afghanistan, through the coordinated use of both air and ground fire in a series of engagements," it said in a statement.
Afghan defence ministry spokesman Mohammad Zahir Azimi told AFP that NATO bombed the insurgents just two kilometres from the Pakistan border in Barmal district. Afghan ground forces also attacked, he said.
"Initial battle damage estimates indicate as many as 150 insurgents were killed," ISAF's statement said.
The defence ministry put the toll at around 80 suspected militants.
ISAF said Pakistani military liaison officers were kept fully informed throughout the operation.
The strike comes amid a row between Afghan and Pakistani officials about ways to curb the cross-border movement of Taliban-linked militants waging an insurgency in Afghanistan.
After complaints from Kabul that it is not doing enough to stop the fighters from crossing over from bases and training camps in Pakistan, Islamabad has proposed fencing and mining parts of the porous frontier.
Afghanistan has strongly rejected the plan, saying Pakistan would do better addressing the roots of extremism such as supporters of militant training camps.