Militants will start killing a group of hostages Saturday if the government does not release several insurgent prisoners, a Pakistani Taliban spokesman said.
A suspected militant leader is among those the Taliban want freed.
Maulvi Umar claimed Friday the Taliban had kidnapped 29 people, most of them security forces. However, Hangu district official Haji Khan Afzal said only 16 or 17 people were being held.
The two sides have been negotiating over the captives, who Afzal said were taken in the wake of a militant siege of a local police station earlier this week in the country's volatile northwest.
Officials said more than 100 militants surrounded the Doaba station to demand their associates be freed, and the siege ended after army troops appeared.