Fresh clashes broke out Monday between troops on the Afghanistan-Pakistan border, where soldiers from both countries exchanged gunfire last week.
Afghan officials said the fight broke out after Pakistani troops returned to the site of a gate on land that both sides claim along the porous border. It is not clear whether there were any casualties in Monday's fighting.
Last week, crossfire on the border killed one Afghan border guard and wounded two Pakistani security personnel.
Pakistan and Afghanistan have blamed each other for starting the firing late Wednesday on what is a crucial battleground in the fight against the Taliban militants who operate in both countries. Officials say the artillery exchange lasted several hours and focused on the disputed gate area.
The Durand Line:
Colonial-era border that separated British India and Afghanistan
More than 2,400 kilometers long, separates modern Afghanistan and Pakistan
Recognized by Pakistan, but not by Afghanistan
Established in a 1893 agreement
Cuts through Pashtun tribal areas
Afghan President Hamid Karzai has called on the Taliban to fight Afghanistan's enemies instead of "destroying their own country." The remarks in Kabul on Saturday did not mention Pakistan directly, but were widely seen as a swipe against it.
Afghanistan and Pakistan have had tense relations since Pakistan's formation, and Pakistan helped the Taliban take power in Afghanistan in the 1990s.
Afghan officials say Pakistan has a long history of of supporting Afghanistan's Taliban and other insurgent factions. Pakistan has, in turn, accused Afghanistan of giving safe haven to militants on the Afghan side of the border.
Both countries are U.S. allies in the fight against militants.
The 2,640 kilometer porous border area known as the Durand Line cuts through Pashtun tribal areas, separating modern Afghanistan and Pakistan. Established in a 1893 agreement, it is recognized by Pakistan but not by Afghanistan.