Pakistani helicopter gunships pummeled several bases of a key Taliban commander in the country's northwest Thursday, killing at least 12 insurgents, intelligence officials said.

The assault came as government forces ratchet up pressure on the northwestern militant network in the wake of Pakistani Taliban chief Baitullah Mehsud's reported death in a CIA missile strike on Aug. 5.

Military helicopters destroyed several bases and hide-outs Thursday morning near the Kurram and Aurakzai tribal regions run by militant commander Hakimullah Mehsud, three intelligence officials said.

Hakimullah Mehsud is a clansman and top deputy to Baitullah Mehsud and is considered a possible successor as top Taliban leader.

The attacks were on bases in tribal areas near the Afghan border, about 60 miles north of the Mehsud clan's main base in south Waziristan.

The intelligence officials, who sought anonymity because they were not authorized to speak to the media, said troops saw the bodies from the air but did not retrieve them. Several militants were also wounded, and the casualties could rise because some people were believed to be still buried under the rubble of their hide-outs, they said.

Thursday's assault followed fierce clashes between fighters loyal to Baitullah Mehsud and those of a pro-government warlord, Turkistan Bitani, on the fringes of the South Waziristan region. At least 70 people were reported killed.

Pakistan's army later sent in helicopter gunships as reinforcements to pound about 300 Taliban fighters attacking Bitani's mountain stronghold, two intelligence officials said. They also spoke on condition of anonymity because they were not authorized to talk to the media.

It was impossible to independently confirm the death toll, as the fighting was taking place in a remote mountainous area that is off-limits to journalists.

The fighting followed days of confusion and competing claims over Baitullah Mehsud's fate. While U.S. and Pakistani officials say they are almost certain he is dead, Taliban commanders insist he is alive.

Baitullah Mehsud and his followers have been the target of both U.S. and Pakistani operations aimed at ridding the country's volatile northwest of militants. Washington has increased its focus on Pakistan's rugged tribal regions because they provide safe haven for insurgents fighting international forces across the border in Afghanistan.