Pakistan on Wednesday hit out angrily at a leaked NATO report accusing its spies of secretly aiding the Afghan Taliban, saying that pre-dawn air strikes killed at least 20 local Taliban fighters.

Pakistan's alliance with the United States and NATO plummeted to an all-time low after US air strikes killed 24 Pakistani soldiers on November 26 and Islamabad has since shut its Afghan border to NATO supply convoys.

Relations with Afghanistan are also notoriously frosty over mutual blame for insurgencies plaguing both countries, but top-level talks in Kabul on Wednesday had been aimed at charting new cooperation.

But the leaked NATO document claims that Islamabad, via Pakistan's ISI intelligence agency, is "intimately involved" with the insurgency and that the Taliban assume victory is inevitable once Western troops leave in 2014.

The BBC said the report was based on material from 27,000 interrogations of more than 4,000 captured Taliban and Al-Qaeda operatives.

"Pakistan's manipulation of the Taliban senior leadership continues unabatedly," the report was quoted as saying.

Taliban captives said Islamabad was using a web of intermediaries and spies to provide strategic advice to the Taliban on fighting US and NATO troops.

"This is frivolous, to put it mildly. We are committed to non-interference in Afghanistan and expect all other states to strictly adhere to this principle," Pakistani foreign ministry spokesman Abdul Basit told AFP.

A senior security official condemned the leak, as reported by the BBC, which also broadcast a documentary "Secret Pakistan" last year accusing parts of Pakistan's intelligence service of complicity with Taliban militants.

"The report is not available, leaks not worth commenting," he told AFP.

A meeting Wednesday between Afghan President Hamid Karzai and Pakistani Foreign Minister Hina Rabbani Khar was likely to be overshadowed by the NATO report, despite being billed as an effort to get relations back on track.

"We are also committed to an Afghan-led and Afghan-owned reconciliation process," Pakistan's foreign ministry spokesman said.

Wednesday's talks follow reports that Islamabad and Kabul are keen to open peace talks with the Taliban in Saudi Arabia, separate to US talks in Qatar.

Both countries are wary of being sidelined from American peace efforts, focused first on securing an exchange of prisoners with the Taliban.

Over the last week, Pakistan has stepped up fighting in its tribal badlands on the Afghan border, where Pakistani and Afghan Taliban, Al-Qaeda operatives and other Islamist militants have carved out strongholds.

Fourteen soldiers have been killed in a bid to restrict the Taliban in Orakzai and Kurram districts, en route to North Waziristan, Pakistan's premier militant bastion where Islamabad has resisted US pressure to wage an offensive.

Security officials told AFP that Pakistani warplanes carried out pre-dawn air strikes killing at least 20 Taliban insurgents on Wednesday and that there were reports that a key Pakistani Taliban commander was among the dead.

Independent confirmation of death tolls is largely impossible in the tribal belt, a Taliban and Al-Qaeda stronghold barred to journalists and aid workers.

The officials said jets bombed four hideouts in Orakzai belonging to Tehreek-e-Taliban Pakistan (TTP) commanders Mulla Tufan and Moinuddin at around midnight (1900 GMT Tuesday).

"Bases of TTP commanders Mulla Tufan and Moinuddin were destroyed. Reportedly, commander Moinuddin, along with more than 20 terrorists, have been killed," one of the officials told AFP.

The bombing comes in the wake of clashes between security forces and militants in neighbouring Kurram in the Jogi mountains, where the military says 52 insurgents and 14 soldiers have been killed since January 25.