KABUL (Reuters) -- The NATO-led International Security Assistance Force (ISAF) in Afghanistan has said its helicopters were fired on from a Pakistani military checkpoint along the eastern border.
There were no reports of any damage to the helicopters or any casualties, it said.
"ISAF helicopters received small-arms fire from a Pakistan military checkpoint along the border near Tanai district, Khost [Province] on September 25 while conducting routine operations in Afghanistan," ISAF said in a statement.
"At no time did ISAF helicopters cross into Pakistani airspace," it said.
Frustrated by an intensifying Taliban insurgency in Afghanistan, the United States has stepped up attacks on militants in Pakistan with six missile attacks and a helicopter-borne ground assault this month.
Pakistan strongly condemned the raids and said it would not tolerate any infringement on its territory. The Pakistani Army has vowed to stand up to aggression across the border.
Most ISAF troops in eastern Afghanistan are U.S.
ISAF said it was working together with the Pakistani military to resolve the latest incident. Pakistani military spokesmen were not immediately available for comment.