Pakistan troops backed by war planes launched a new operation in Buner town near the Swat valley Tuesday, as Islamabad intensified its efforts to flush out Taliban militants there.
"The military launched an operation at 4:00 pm (10:00 GMT) today," chief military spokesman Major General Athar Abbas told a news conference.
"The army and the Frontier Corps troops have entered Buner," he said, adding that "fighter jets are also being used."
A senior military official earlier told AFP that war planes were pounding suspected militant hideouts on the mountains overlooking the town, but he had no casualty figures.
The latest operation follows an offensive mounted in Lower Dir on Sunday, which Abbas said had now been completed.
He added 70-75 militants had been killed in that operation and that "10 security personnel have been martyred."
Abbas said that while there "are no foreign militants in Swat," intelligence reports said that "militants are getting weapons and communication equipment from outside Pakistan."
"They are using Kalashnikovs, small arms, rocket launchers, grenades, mines and explosives."
Reporters were also shown the transcript of a telephone conversation between radical cleric Maulana Fazlullah and a military commander in which they planned a "symbolic" withdrawal of militants from Buner.
The Dir military offensive has meanwhile led to the displacement of around 30,000 people, Mian Iftikhar Hussain, information minister in the government of North West Frontier Province, said.
Witnesses said thousands of terrified people, mostly women and children, left the area with their belongings after troops and helicopter gunships launched the operation over the weekend.
Residents in Buner said they heard bombs exploding in Karahar and Babaji Kandao, located between the districts of Swat and Buner.
Local authorities had declared an indefinite curfew before troops entered Buner, police chief Rasheed Khan said.
Abbas said the military was trying to eliminate rebels from the town, which lies around 75 kilometres (46 miles) south of Swat valley.
In February, the government agreed that Islamic sharia law could be enforced in Swat and its surrounding districts in the Malakand region.
The deal with militants was aimed at ending two years of rebellion during which followers loyal to Fazlullah beheaded opponents and torched girls' schools.
But Abbas said that an advance by up to 500 Taliban into Buner earlier this month was a "violation" of the February agreement, and that they were harassing and terrorising the local population.
The Taliban's advance saw Washington brand the extremists "an existential threat" to Pakistan.
US Secretary of State Hillary Clinton warned that Pakistan was "basically abdicating to the Taliban and to the extremists." US Secretary of Defence Robert Gates called on the country's leaders to take action.
The Taliban suspended peace talks with the government Monday after the military launched Operation Black Thunder following intense US pressure to stop the extremists' advance.
Information minister Hussain said the government remained "determined to fully implement the deal but some outsiders who do not want peace have infiltrated in Buner and Dir districts to sabotage the accord."
He invited hardline Islamist cleric Soofi Mohammad, who negotiated the Swat sharia law deal, to resume talks to avoid any delay in its implementation.
Taliban spokesman Amir Izzat Khan earlier warned the operation in Lower Dir could endanger the peace deal.
"There can be a reaction to the government action," he told AFP.
However, President Asif Ali Zardari said Monday the peace deal with the Taliban remained valid until the North West Frontier Province government told him otherwise.
"There will be a reassessment of the situation by the provincial government and if needed we'll come back to parliament and the parliament will decide," he said in an interview with foreign journalists.