The Pakistani army says troops entered the heart of Swat Valley on Saturday, pushing into the town of Mingora, a Taliban stronghold.
Top army spokesman Major General Athar Abbas says Pakistani security forces are engaged in fierce street battles in Mingora and have already cleared some areas of the district capital.
Major General Abbas told reporters on Saturday the military advance into Mingora has routed out Taliban control.
"Miscreants, terrorists are on the run in small groups in the [Swat] Valley after the successful operation by the security forces," he said. "The locals of Puchar [region] reveal that they were subjected to forced labor and atrocities by miscreants, terrorists."
Major General Abbas also told reporters that clearing operations are under way in some parts of Mingora and that 17 militants, including a top commander, have been killed over the past 24 hours. He said a would-be suicide bomber was killed and bomb-laden vehicle was destroyed.
The fight for control of Mingora marks a crucial moment in the military campaign in Swat, launched earlier this month to stop the spread of a Taliban insurgency.
The loss of territory to militants over the past two years in the scenic ski resort region prompted officials to make a deal with radical Islamic cleric Sufi Mohammed.
But the government officially ended the agreement in early May after militants quickly moved into Buner, south of Swat, and refused to lay down their arms. The United States pressured the government to go after the Taliban militants, raising alarm that they had advanced within 100 kilometers of the capital, Islamabad.
So far, the army says more 1,095 militants have been killed - a number that has not been independently verified.
The military offensive has unleashed a humanitarian crisis in Pakistan, displacing nearly two million people. On Friday, the United Nations appealed for an additional $454 million to assist those who have fled the violence, saying Pakistan is experiencing the biggest displacement of its people in the country's history.