Afghanistan's foreign minister appealed to Pakistan to stop interference in his country, complaining that unnamed powers across the border are supporting terrorism.
"My appeal to our brothers in Pakistan is to stop interfering ... To stop these powerful sectors which use terrorism as an instrument of foreign policy," Afghan Foreign Minister Rangeen Dadfar Spanta said in an interview.
He said NATO and Afghan government forces could halt Taliban attacks if they received "constructive participation" from Pakistan.
The Afghan government has long complained that Taliban insurgents are allowed to freely cross the border to mount attacks in southern and eastern Afghanistan, then flee back to sanctuary in Pakistan.
Pakistan strongly denies the accusation.
Pakistani President Gen Pervez Musharraf said accusations that Pakistani military and intelligence officials may have helped Taliban fighters cross the border were "preposterous", saying he had sent tens of thousands of troops to secure his side of the Afghan border.
NATO is seeking closer cooperation between its force of nearly 33,500 troops in Afghanistan and Pakistani authorities.
Prime Minister Shaukat Aziz is due in Brussels on Tuesday in the highest-level visit by a Pakistani official to allied headquarters.
Spanta said NATO should use the occasion to press the Pakistanis to secure the border.