GHALANAI, May 6: Afghan forces attacked a border checkpost in Mohmand Agency on Monday, injuring four Pakistani soldiers.

Security sources said the Gursal checkpost was attacked at around 9am with rockets, mortars and other heavy weapons. Pakistani forces retaliated and the exchange of fire lasted over two hours.

This was a second attack from across the border in a week. Two Pakistani troops were injured when Afghan forces attacked the Gursal and two other checkposts four days ago.

Agencies add: Clashes last Wednesday in the same area also killed an Afghan guard.

Afghanistan and Pakistan are in dispute over a site where Pakistan has tried to build a gate on what Afghan officials claim is Afghan territory.

“Today the Pakistanis returned to the construction site and said they will rebuild the installations,” said Afghan interior ministry spokesman Sediq Sediqqi.

“Our border police told them not to do so. The Pakistanis fired at them and our police returned fire. The fighting lasted for two hours before the Pakistanis requested a ceasefire,” the spokesman added.

He said the clashes had since stopped and the Pakistani border guards had left the site of the construction.

Pakistani officials blamed Afghans for starting the clashes. “Afghan troops opened unprovoked fire from across the border at our post... They fired mortars and automatic weapons,” one Pakistan official told AFP.

“Our troops responded with retaliatory fire. There have not been reports of any casualties so far. The exchange of fire continues at intervals,” a second official said, also on condition of anonymity.

The Afghan government summoned a senior Pakistani diplomat to lodge protest.

The Afghan foreign ministry said it summoned the Pakistani charge d’affaires to protest the “unprovoked attack by Pakistani forces”.

Pakistan would bear the responsibility for “any consequences” in case of further attacks on Afghanistan, it said in a statement.

On the edge of Kabul, more than 2,000 people, mostly villagers, demonstrated to protest against the fighting.

On Saturday, Afghan President Hamid Karzai alleged that cross-border clashes could be an attempt by Islamabad to put pressure on Kabul to accept the “Durand Line”, the disputed border which Afghans do not accept.

Pakistan’s foreign ministry dismissed Mr Karzai’s remarks and said “opening discussions on this issue” was a “distraction from the more pressing issues requiring the priority attention and cooperation of Pakistan and Afghanistan”. It said Pakistan’s checkpost had come under attack and complained about “several threatening and provocative statements” from Afghan leaders.