Suspected Taliban stormed a depot handling supplies for NATO troops in Afghanistan on Wednesday and torched eight trucks, as Pakistani troops and warplanes battled militants in a swath of the northwest.

Dozens of attackers poured into the transport terminal near the northwest city of Peshawar and set the trucks ablaze before fleeing, police official Ghafoor Khan Afridi said.

Firefighters quickly doused the flames, and metal shipping containers holding NATO supplies were unscathed, he said.

Attacks on terminals and trucks rolling through the Khyber Pass toward Afghanistan have intensified since last year, adding to concern that more and more regions along the Afghan border are slipping from government control.

NATO and U.S. commanders insist that their losses have been minimal and pose no threat to their expanding military operation in Afghanistan. Still, they have begun seeking alternative routes through Central Asia.

The latest incident comes as Pakistan's army is embroiled in a major operation — launched under intense U.S. pressure — to evict Taliban militants from the Swat Valley and two other districts uncomfortably close to the capital, Islamabad.

On Tuesday, the military said helicopters dropped commandos behind Taliban lines in Swat and claimed that it had killed more than 750 militants since the operation began in late April.

But the military acknowledged it had yet to start operations in the region's main town of Swat, where witnesses say Taliban insurgents are in control and preparing for what could be bloody door-to-door fighting.

The latest conflict has prompted an estimated 800,000 people to flee their homes, in addition to a half-million refugees from earlier military offensives in the northwest, and adding a humanitarian emergency to Pakistan's mounting problems.