Pakistani security forces have begun a fresh military operation in the northwestern part of the country, RFE/RL's Radio Mashaal reports.
The operation was launched on October 11 in the Katlang area outside Mardan, the second-largest town in Khyber Pakhtunkhwa Province.
Army officials say the villages and mountainous areas are being combed for militants believed to have fled from the nearby Swat region.
A spokesman for the Inter-Services Intelligence (ISI) agency's public relations office told RFE/RL that four militants were killed and several others taken into custody during the operation.
"Those arrested will be investigated and those found innocent will be freed later," the spokesman said.
The Katlang area borders Malakand, the region where Pakistani security forces conducted a massive military operation in May 2009. Thousands of people from Swat temporarily migrated to Katlang and other parts of Mardan during the three-month operation.
Waqif Khan, a senior police officer in Mardan, told RFE/RL that the operation was carried out jointly by police and the army.
"This operation is being conducted in all villages. The people have to undergo screening," Khan said. "Those suspected of involvement in terrorism are taken into custody and those who are innocent are released."
Residents of the area complained they were restricted to their houses because of the military operation. They said the troops were searching houses and detaining people who don't have their national identity cards.
Katlang resident Shad Muhammad said widespread fear existed among the people following the arrival of the army commandos in helicopters.
"The Katlang bazaar is closed due to a curfew and people are facing serious problems," he said. "People can't even move their relatives to the hospital if someone gets sick. There are also problems in getting food."
The operation was launched days after the killing of an outspoken religious scholar inside his office in the town of Mardan by unknown militants.