A day-long clash between militants from Afghanistan who crossed the border and attacked a Pakistani checkpoint has left 23 troops and 35 insurgents dead, police have said.
The fighting came as a top Pakistani general said the military plans to stage an operation against militants in a tribal region which cuts deep inside Afghanistan, but denied media reports of a forthcoming offensive in North Waziristan.
Pakistan's north-west border with Afghanistan has for years been a stamping ground for Islamist extremists. Pakistan has taken action against the latter groups but they have retained the ability to strike back, partly because the border is so porous and insurgents under attack can easily cross from side to side.
The clash began in Shaltalo town in Upper Dir district on Thursday. Upper Dir lies just outside the tribal belt, but it too has witnessed al Qaida and Taliban militant activity and been the focus of military offensives.
Police said some 200 militants crossed over into Pakistan from Afghanistan, and went after a checkpoint manned by police and paramilitary troops. At least 23 Pakistani security troops died and three were wounded, while 35 militants were killed, said police official Johar Khan.
Army Lieutenant General Asif Yasin Malik, who oversees military operations in the tribal areas and other parts of the north-west, said the Kurram tribal area would be the next target of an offensive after local leaders there requested it. He said operations would be launched there with the government's backing, but declined to give any more operational details.
Kurram has seen sectarian violence between Shiite and Sunni Muslims for years, but is also home to militants with other aims. According to some accounts, the Haqqani network, a faction of the Afghan Taliban, was shifting fighters there from North Waziristan tribal region.
The Haqqani network is considered one of the biggest threats to US forces in Afghanistan, partly because its fighters can retreat across the border to North Waziristan, where they have bases and have been left alone by the Pakistani army.
The US has pushed the Pakistani military go after the Haqqanis and other factions in North Waziristan. But Lt Gen Malik dismissed recent "media hype" about an imminent offensive in North Waziristan.
"There is no change in North Waziristan in past months and weeks," he said. "We will undertake an operation when we want to, when it's in the national interest."