Officials in Pakistan say the military has killed 20 militants and destroyed their positions during an air raid near the Afghan borders.

The military used helicopter gunships Sunday in the tribal district of Orakzai, an area controlled by top Taliban commander Hakimulah Mesud.

The operation was launched on Sunday and at least four militant positions have been destroyed so far, a military official said.

The operation follows Saturday's suicide bombing attack in the nearby town of Hangu that killed 25 people, most of them are soldiers and police.

Hakimulah Mesud claimed responsibility for the attack, saying the assault was carried out to avenge U.S. missile strikes by unmanned aircraft against militants.

We will continue to launch suicide attacks until U.S. Aircraft attacks are stopped, he said in a telephone call to reporters.