The militants launched a midnight attack in the Bezoti area in a bid to recapture a camp lost to security forces two days ago, said Col. Tahair Ikram of the Frontier Corps.
"Over 100 militants from Orakzai and the neighboring Khyber region attacked security forces around midnight, triggering a firefight that continued for hours," he said.
Another security official said at least 15 militants were killed and four captured. One soldier was wounded in the attack.
A semi-autonomous region, Orakzai has become a Taleban hub following offensives by security forces over the past year that uprooted militants from their strongholds in other parts of the mainly Pashtun northwest.
Pakistan, an important US ally, has recently stepped up assaults in Orakzai, prompting militant retaliation.
Troops have killed about 250 militants in nearly two weeks of fighting in Orakzai, an early stronghold of Pakistani Taleban leader Hakimullah Mehsud, widely believed to have been killed in a US drone strike in the North Waziristan region on the Afghan border in January.
Pakistani action against militants along the Afghan border is seen as crucial to US efforts to bring stability to Afghanistan, particularly as Washington sends more troops to fight a raging Taleban insurgency before a gradual withdrawal starts in 2011.
Despite government assertions the security forces have taken control of most Taleban bases, militants have exhibited the ability to hit back, attacking government targets and killing hundreds of people in a campaign of suicide bombings.
Police shot dead a suicide bomber on Friday while his companion blew himself up during a firefight, which erupted after they were spotted in Lakki Marwat, a town in Bannu district which is a gateway to North Waziristan.
