The two-hour battle erupted after Afghan forces fired a mortar at Pakistani soldiers near the Teri Mangal area in the Kurram tribal district, Pakistani military spokesman Major General Waheed Arshad told AFP.

"The exchange of fire continued until 5:00 am. There was a brief resumption of firing around 7:00 am, but it ended quickly," he said, adding that there were no Pakistani casualties and that he was unaware of any on the Afghan side.

The Afghan ministry of defence said 20 rockets were fired at Afghan military bases and that two members of its security forces were wounded.

The incident happened near an area where a US soldier and a Pakistani trooper were shot dead on Monday after a meeting, also involving Afghan officials, that was aimed at calming tensions.

The Nato-led International Security Assistance Force (Isaf) in Afghanistan said Wednesday there were reports the gunman was in Pakistani paramilitary uniform. It demanded that Pakistan investigate the incident.

Thursday's fighting had been reported to a joint intelligence centre set up last year between Afghan, Pakistani and Nato forces, Isaf spokesman Major John Thomas said.

"They are involved in trying to resolve it," he added.

Afghan President Hamid Karzai called for the clashes to cease, adding that he had ordered his forces not to use artillery fire, even if provoked, to avoid civilian casualties.

"We want an end to these skirmishes. It is not in the interest of any country," he said at a joint news conference with visiting Danish Prime Minister Anders Fogh Rasmussen.

"Afghanistan will continue to cooperate but at the same time will continue strongly to defend the country."

Afghan officials have accused Pakistan of starting clashes in the same area on Sunday that continued into Monday, saying Pakistani troops pushed four kilometres (2.5 miles) over the disputed border. Pakistan denied the charges.

Thirteen Afghans were killed in the fighting, which included rocket fire, Afghan officials said.