The hostages were seized in Kurram after the vehicles they were travelling in were ambushed by men reportedly dressed as police officers.

Women and children were among those taken captive, according to the police.

Kidnappings for ransom are common in the Islamic militant stronghold of Kurram, which borders Afghanistan.

Heavily armed militants seized several vehicles that were travelling in convoy to Parachinar, the main city in Kurram, said Mir Chaman, the area police chief.

"The militants were posing as policemen and wearing police uniforms," he said.

An investigation was under way and all efforts were being made to find the hostages, he added.

There has been no claim of responsibility for the attack.