A U.S. drone fired two missiles on Thursday at a compound in northwest Pakistan where the Pakistani Taliban chief was believed to have been, but intelligence officials said chief Hakimullah Mehsud was not among the 12 militants killed.

The missiles slammed into a former school where Pakistani Taliban leaders were meeting Thursday. Reports quickly circulated that Mehsud had died.

However, three intelligence officials and four militants told The Associated Press that he was alive. The officials said they gleaned the information from wireless communications intercepts. It was unclear whether Mehsud was ever at the meeting.

The sources all spoke on condition of anonymity because of the sensitivity of the subject.

A Pakistani Taliban spokesman told Dawn TV that Mehsud was safe and had left minutes before the strike.

"Hakimullah Mehsud was present at the same place in Shaktoi where the drone attack took place," a Taliban spokesman told AFP by phone. "But he had left the place already when the drone attack took place. He is alive and completely safe."

Mehsud took over as leader of the Pakistani Taliban last August after his predecessor, Baitullah Mehsud, was killed in a similar U.S. drone strike.

The group denied Baitullah Mehsud's death for weeks, apparently amid fierce infighting over his succession.

The strike illustrated the Obama administration's unwillingness to abandon its missile campaign against insurgent targets along Pakistan's northwest border with Afghanistan. Despite Pakistani protest, the attacks have surged in number in recent days.

Nearly all the attacks in recent months have focused on North Waziristan, a segment of Pakistan's semiautonomous tribal belt where militant networks focused on battling the U.S. and NATO in Afghanistan are based. Some of those militants are believed to have been involved in a late December attack that killed seven CIA employees in eastern Afghanistan.

It's a region that the Pakistani military has been wary of treading, partly because groups based there have not directly threatened the Pakistani state. The army has struck truces with some of them to keep them out of its battle against the Pakistani Taliban — who have attacked Pakistan in numerous ways — in neighboring South Waziristan.

At least two missiles hit the Pasalkot area of North Waziristan around 7 a.m., landing in a sprawling compound that has been used as a religious school in the past. The identities of the dead were not immediately known, an army official and an intelligence official said.

The strike came as Richard Holbrooke, a U.S. special envoy to Pakistan and Afghanistan, was visiting parts of Pakistan.

The U.S. rarely discusses the covert missile campaign, though in the past American officials have lauded it as a successful tactic that has killed several top Al Qaeda operatives as well as Pakistani Taliban chief Baitullah Mehsud.

Pakistan formally protests the drone-fired strikes, saying they violate its sovereignty and spur more anti-American sentiment among the population, but many analysts believe the nuclear-armed South Asian nation secretly aids the campaign.

During a Wednesday media conference with Holbrooke, Pakistani Foreign Minister Shah Mahmood Qureshi stopped short of completely ruling out the missile attacks, but said there were certain "red lines" that Washington must not cross.

"Pakistan feels that it would undermine our relationship if there is expansion of drones and if there are (U.S.) operations on the ground," Qureshi said.

The Associated Press contributed to this report.