Pakistani warplanes have pounded militant positions in North Waziristan, as fighting raged for a fourth day in a tribal region known as an al-Qaeda and Taliban stronghold, an army spokesman said.
There has been intense fighting since Saturday night around the town of Mir Ali, and nearly 200 people had been killed before yesterday's air strike.
Thousands of families were fleeing the town of 50,000 and outlying villages, making their way on foot, in tractor trailers and cars.
The army had no details of casualties from yesterday's air strike, though residents and a security official in North Waziristan put the number of people killed at close to 50.
Violence has surged in the lawless Waziristan region since militants scrapped a peace deal with authorities in July.
Attacks by suicide bombers have become commonplace, especially after the army stormed a mosque in Islamabad in July to crush an armed student movement.