A general view of the border post in Torkham, Pakistan. File / Reuters

Pakistani closed the Khyber Pass border crossing with Afghanistan for 10 hours on Wednesday after mortar bombs landed in Pakistani territory from across the border, an official said.

The Torkham crossing, through which thousands of vehicles pass every week, is the main trade link between the uneasy neighbours.

In September last year, Pakistan opened the crossing for 24 hours a day to boost trade.

"Some mortars were fired from across the border in Afghanistan and landed inside Pakistan. They caused some damage to vehicles," Mahmood Aslam Wazir, deputy district commissioner of the area on the Pakistani side, told Reuters.

Exchanges of fire across the border, which Afghanistan has never recognised, are common. But an Afghan official denied that Afghan forces had fired into Pakistan.

Trucks carrying shipping containers wait to cross into Afghanistan at the border post in Torkham. File / Reuters 

Hundreds of vehicles that had been stuck on both sides began moving across the border on Wednesday afternoon after the crossing was reopened, Pakistani and Afghan officials said.

Wazir was not immediately available for comment on the findings of the investigation.

Pakistan was angered this week when Afghan President Ashraf Ghani condemned the arrest in Pakistan of an ethnic Pashtun rights activist.

Reuters