The dead include Arabs, Uzbeks and local fighters who also took part in attacks inside Afghanistan.
Pakistani security forces backed by helicopter gunships struck the facility before dawn on Saturday in the North Waziristan town of Drub Lokai, a tribal region near the Afghan border.
Twenty-two Arabs, three Uzbeks and seven local tribal fighters linked with al-Qaeda and the Taliban were among those killed in the attack, a senior Pakistani security official said on condition of anonymity because of the sensitive nature of the information.
Initial reports on Saturday put the death toll at 15-20 people.
"It was a highly successful operation," said Pakistan army spokesman Major-General Shaukat Sultan.
North Waziristan has witnessed an increase in attacks by al-Qaida and Taliban supporters against Pakistani forces.
Osama bin Laden and other wanted fugitives are believed to be hiding in the rugged Pakistan-Afghan frontier region.
Pakistani forces said they had
been monitoring the site for days
The security official said the slain fighters had been involved in attacks in Afghanistan and had launched rocket attacks and roadside bombings against Pakistani troops in North Waziristan.
The camp itself had a firing range.
Pakistani forces had been monitoring the fighters' activities for several days before launching Saturday's strike as the fighters were preparing to leave in pickup trucks, the official said.
Among those killed was the purported insurgent commander, identified only as an Arab by the name of Abu Nasir, the official said.
No further details were available on either the victims or their nationalities.
Arab toll biggest
The official said the number of Arabs killed was the largest in any one attack inside Pakistan.
The fate of the bodies was unclear, with different officials saying they were taken to a hospital in North Waziristan or hastily buried by other fighters.
Military spokesman Sultan said the attack was conducted solely by Pakistani soldiers and did not involve American forces as reported by Pakistan's Dawn newspaper, which quoted unidentified sources saying that US warplanes may have carried out the strike.