ISLAMABAD, Pakistan - Pakistani warplanes and ground forces killed 39 militants as part of an operation in a volatile tribal region near the Afghan border, the Pakistani military said.

The airstrikes were carried out Friday in the Datta Khel area of the North Waziristan tribal region, an army statement said Saturday, adding that an underground tunnel system and a large underground cache of weapons and ammunition were also destroyed.

The military contended that several important militant commanders were among the dead, but didn't provide further details on the identities of the slain militants.

Also late Friday, Pakistani troops ambushed a large assembly of militants on the border between the Orakzai and Khyber tribal regions, the statement said. An intense battle took place, it said, in which 16 militants were killed and an additional 20 injured. Four army soldiers were also injured in the shootout, it said.

Journalists are barred from the region, and it is impossible to independently verify the information.

The army says it has killed more than 1,200 militants since the start of a massive offensive launched June 15 against militants in North Waziristan. It was begun after a terrorist attack on Pakistan's largest airport in Karachi.

The North Waziristan tribal region is one of seven tribal regions near the Afghan border where local and foreign militants have found safe haven for years. A parallel government offensive is taking place in the neighboring Khyber region to pursue militants fleeing North Waziristan.