Afghan and Pakistani forces fired at each other over the border Monday, the second clash in less than week, an Afghan army official said, dpa reported.
The clash occurred at Afghanistan's eastern border with Pakistani tribal areas, where the first skirmish happened Wednesday.
"I can say that Pakistani troops targeted the Afghan border police checkpoints this morning, using artillery, tanks and other heavy arms," said Noman Atefi, spokesman for the Afghan National Army in the eastern region.
"The border police responded and the exchange lasted for more than two hours," Atefi told dpa, adding that there were no reports of casualties.
NATO spokesman Guenter Katz said international forces would work with both sides to assess and contain the problem.
"We exchange views, we assess the situation and see how we can together de-escalate and how can together improve the security situation at the border," Katz said in Kabul.
One Afghan policeman was killed and another one injured in the clash last week. Afghanistan blames Pakistani troops for building a gate inside Afghan territory in violation of national sovereignty.
The two countries have a delicate relationship over the British-designated Durand Line. Afghanistan does not recognize the line as the border, while Pakistan and most Western countries do.