The clash erupted in the Nari district of Kunar.
According to the source, the Pakistani forces opened fire first, and Afghan reinforces are currently on the way to support the attacked troops.
Further details of the incident remain unknown.
The Durand Line is an over 1,500-mile border between Afghanistan and Pakistan, whose outskirts are known to be a hotbed for terrorist and militants groups, including the Taliban Islamist movement.
