Pakistani helicopter gunships pounded militant targets in the country's northwest Friday, killing up to 20 rebels, as the number of civilians fleeing an expected ground offensive passed 150,000.
Nearly 100,000 people have left North Waziristan tribal area, on the Afghan border, this week after the military launched a long-awaited assault against Taliban hideouts.
The authorities eased a shoot-on-sight curfew on Wednesday to give civilians a chance to leave before troops begin a full-blooded ground operation.
A senior security official told AFP that helicopter gunships targeted militant hideouts in an early morning raid in Kutabkhel area of Miranshah, the main town of North Waziristan, killing up to 20 militants.
A local intelligence official also confirmed the attack and casualties.
Nearly 250 insurgents have been killed since the start of the operation on Sunday, according to security officials, though it is not possible to confirm the number or identity of those killed.
The military offensive began after a bloody and dramatic attack on Karachi airport last week brought an end to months of largely fruitless government efforts to negotiate a peace deal with the Tehreek-e-Taliban Pakistan (TTP).
Washington has long demanded action against militant hideouts in North Waziristan, which has served as a rear base for insurgents battling US-led forces in Afghanistan, but Pakistan resisted.
The area, one of seven semi-autonomous tribal regions on the Afghan border, has been an important base for the TTP, which has killed thousands in bombings and gun attacks during its seven-year insurgency.
The fighting has triggered a huge exodus of civilians from North Waziristan, both into the Pakistani cities of Bannu, Peshawar and Kohat and across the border into Afghanistan.
"Some 157,000 people have arrived in Bannu from different areas of North Waziristan," Arshad Khan, director general of the FATA (Federally Administered Tribal Areas) Disaster Management Authority, told AFP on Friday.
Registration points and camps have been set up to deal with the influx of people in Bannu, but many prefer to travel on to stay with relatives in other areas.
Thousands of people including women and children were seen travelling to Bannu by foot on Friday morning. Women were sitting along the roadsides as vehicles and passenger vans kept moving at a snail's pace in long queues.
So far there appears to have been little resistance from the TTP to the military operation, though this may change once the ground fighting begins.
In Torghar district, around 130 kilometres (80 miles) northwest of Peshawar, a roadside bomb targeting a police van killed one policeman and wounded two others.