At least 15 security personnel were killed and several others were injured when militants attacked a check post in northwest Pakistan, media reports said on Friday.
Militants armed with heavy weapons, including rockets, attacked the check post in Lower Dir district of Khyber Pakhtunkhwa province bordering Afghanistan, killing at least 15 security personnel, Xinhua reported.
Media reports, however, varied about the time of the attack. Geo TV said the attack took place Thursday night, while the Urdu TV channel ARY said it took place early Friday.
Army helicopter gunships later bombed the militants' positions but there were no reports of casualties.
The injured, who were initially taken to a hospital in Timergara, the main town in Dir district, were later shifted to Peshawar, the capital of Khyber Pakhtunkhwa province.
The fighting was still on in the area Friday afternoon, the Urdu channel said.
Officials said Afghan insurgents crossed into Pakistan to back the Pakistani militants in the attack, the biggest in recent months.
About 34 border guards and 10 policemen were manning the post. Both sides exchanged fire for several hours before army helicopters were called in for support.
Local residents fled their homes after the fighting erupted.
Dir district had been a stronghold of the Taliban militants, who were expelled in a major operation in 2009.
Officials believe the militants from the nearby Bajaur tribal region and the Swat Valley have taken shelter in the mountainous Dir region, about 15 km from the Afghan border.
Security has been beefed up in the area as troops prepare for a major operation. A curfew has also been imposed and people were advised to stay indoors.