Thousands of families were leaving the town
of 50,000 and outlying villages

Pakistani warplanes have pounded positions of armed groups in North Waziristan, as fighting rages for a fourth day in a tribal region known to support al-Qaeda and Taliban. An army spokesman said on Tuesday: "Aircraft were used to attack militants' positions near Mir Ali this afternoon."

The spokesman had no details of casualties from the air strike, though residents and a security official in North Waziristan put the number of people killed at close to 50.

There has been intense fighting since Saturday night around the town of Mir Ali, and nearly 200 people had been killed before Tuesday's air assault.

Thousands of families were getting out of the town of 50,000 and outlying villages, making their way on foot, in tractor trailers and cars.