Pakistan President Asif Ali Zardari met the chief of the powerful army on Saturday for face-to-face talks, a spokesman said, amid a civilian-military standoff that is shaking the government.

The unscheduled meeting comes against a background of shaky ties between Zardari's weak civilian administration and the military over a probe into a mysterious memo apparently seeking US help to curb the army's power.

"Chief of the army staff General Ashfaq Kayani called on President Zardari in his office today," the president's spokesman Farhatullah Babar told AFP.

He gave few details about the meeting, but said that the "current security situation came under discussion".

Kayani, widely regarded as the most powerful figure in Pakistan, later attended a scheduled meeting of the cabinet defence committee, chaired by Prime Minister Yousuf Raza Gilani and including senior ministers and military chiefs.

The committee considered a report from a US inquiry into the November 26 attack by NATO helicopters on a border post that killed 24 Pakistani soldiers.

"Pakistan's response to the report will be shared with all concerned shortly," a spokesman for Gilani's office told AFP after the meeting.

It was not immediately clear whether the meeting would lower tension between the civilian and military leadership.

Pakistan has been under military dictatorships for about half its history since independence in 1947, with civilian leaders thrown out in three coups.

But in spite of the current tensions, analysts say another coup is unlikely and they instead predict early elections, possibly in the first half of this year.

The "Memogate" scandal centres on an unsigned note allegedly sent by an aide of Zardari to the US military last May, apparently to avert a possible coup after the killing of Osama bin Laden by the US in Pakistan.

The memo has pitted the army against Zardari's government and the Supreme Court has been tasked with deciding whether the government endorsed the note, and if so, if it can remain in power.

Gilani earlier this week accused the army and intelligence chiefs of failing to make their submissions to the commission investigating the memo through government channels, in an unusually bold interview with Chinese media.

The army vociferously denied Gilani's accusation and said it had passed its response through the defence ministry to the court in accordance with the law, ratcheting up tensions between the two sides.

Saturday's defence committee meeting was to finalise recommendations for new rules of engagement with NATO following the deadly November air strikes, which put further stress on an already fragile relationship between Washington and Islamabad.

Pakistan closed its main trading route to Afghanistan, choking a major supply line for the 130,000-strong US-led force, following the deadly air strike by the alliance force.

Islamabad rejects the coalition's report that blamed the incident on mistakes by both sides and has not said when it will reopen the route.

NATO wants to get relations with Pakistan back on track "as quickly as possible" to reopen its key supply route for foreign troops fighting in Afghanistan, a coalition spokesman said Monday.

In his opening statement to the committee Gilani said: "Pakistan's sovereignty and territorial integrity are non-negotiable."

He said a "full review" of the terms of cooperation with US and NATO was in process.

"We hope that decisions in this regard will be in line with the aspirations of our people and go a long way in preserving and protecting our national interests and promote peace in the region," the PM said.

Gilani also vowed he would do everything to strengthen state institutions with a view to enhancing their effectiveness and capacity. "There should be no ambiguity on this account," he told the committee.