The armed forces have secured control over several key towns during the month-old campaign in the volatile north-western region, but the fighting has uprooted some 3 million people from their homes and triggered a series of suspected reprisal attacks elsewhere in the country.

Chief army spokesman Maj Gen Athar Abbas told reporters on a military-organized tour of Mingora town that it could take another two months of fighting to root the militants from all of their hide-outs in the lush, mountainous valleys of Swat and surrounding areas.

He cautioned, though, that two month timetable was "a rough estimate."

Earlier, Maj Gen Ijaz Awan, a senior commander in the eight-day battle for Mingora, said the military is gearing up for a fight in nearby Kabal town where top Taliban leaders are suspected of being holed up.

"We have bottled them up very well, hopefully this will be a decisive battle here" in Kabal, said Awan. "Their deaths are vital to killing their myth."

The battle for Swat, launched in late April after the militants abandoned a peace deal with the government that gave them control of the region, is seen by Washington as a test of Pakistan's resolve against militants in the north-western border region with Afghanistan.

The United States strongly backs the campaign, and it has enjoyed broad support among Pakistanis tired of militant attacks in the country that have killed hundreds of civilians.

But that support may sour if civilian casualties turn out to be high or if the government is perceived to deal badly with the refugee crisis. The government also has to contend with a rise in militant attacks in other parts of the country that officials say an attempt to distract the military's attention from Swat.

One such attack was Monday night's ambush-kidnap of scores of students from a military cadet school in North Waziristan, near the Afghan border.

Officials said on Tuesday that 80 students and staff had been rescued by paramilitary forces within hours, and that was the total number of those kidnapped.

But Javed Alam, the director of studies at the school, Cadet College Razmak, said on Wednesday that more than 100 people were taken in the raid and that 42 students and three teachers were still being held captive at an unknown place.

Some had been allowed to call their parents, though no ransom or other demands were made, he said. The captors did not identify themselves.

Abbas said the military was did not know until Wednesday that all the students had not been accounted for. "We thought it was over," he said.

Richard Holbrooke, President Barack Obama's special envoy to Afghanistan and Pakistan, was due in the Pakistani capital of Islamabad Wednesday for talks on the offensive and the refugee crisis.

Power, water and gas remain cut in Mingora, the largest in the Swat region, and food is short. Officials are discouraging refugees from returning home yet.

During Wednesday's military tour through parts of Mingora, an AP reporter saw soldiers stationed on streets throughout the town but little sign of civilian life among the 40,000 residents still there.

At a crossroads dubbed "bloody intersection" by locals because the Taliban would leave bloodied bodies of victims there as a warning to others. There were signs of a tough battle. Chunks of one multistory building were blown away, and security gates were torn off at least one storefront. Broken glass and bricks lay all around.