Islamabad: Ignoring fresh calls from the US, Pakistan on Friday said it will not budge from its decision to boycott a key conference on Afghanistan's future in Bonn next week in the wake of a cross-border NATO air strike that killed its 24 soldiers.

Foreign Minister Hina Rabbani Khar said the Cabinet had decided to boycott the Bonn meet and that she did not believe there is a "very strong case to reconsider this decision".

Her remarks came as the Obama administration again called on Pakistan to reconsider its boycott of the Afghan conference on December 5.

US Secretary of State Hillary Clinton said Pakistan's decision not to attend the crucial meet was "regrettable".

Clinton, who was on a historic visit to Myanmar, said that she hoped there would be a "follow-up way" for Pakistan to take part in talks on Afghanistan's future.

She also pledged an investigation "as swiftly and thoroughly as possible" into the "tragic" NATO attack last Saturday.

White House Press Secretary Jay Carney also urged Pakistan to participate in the Afghan meet in the German city of Bonn, which is being attended by Foreign Ministers of over 90 countries to discuss key issues like the withdrawal of foreign forces from the war-ravaged nation and negotiations with the Taliban.

Khar on Friday said that Pakistan could not be part of a process related to another country until it could preserve its own interests.

"We are willing to play a positive role but not at the cost of Pakistan," Khar told reporters outside Parliament, responding to questions on whether the government would review its decision to boycott the crucial Afghan meet.

"How can we push other's interests and what positive role can we play when there is no guarantee of our own sovereignty? There is no basis for joining this process if our territorial integrity, sovereignty and national interests are not protected," she said.

Pakistan responded angrily to Saturday's NATO strike on two military border posts by closing all NATO supply routes and asking the US to vacate Shamsi airbase, reportedly used by CIA-operated drones.

Prime Minister Yousuf Raza Gilani has refused to be swayed by calls from world leaders to reconsider the decision to boycott the Bonn Conference.

Khar said Pakistan's ties with any country or grouping like NATO are based on its national interests and sovereignty and defending its territorial integrity.

After the NATO attack, it would be "impossible" for Pakistan to continue with the "current terms of engagement," she said.

There is a need for a "fundamental change" in the terms of engagement and the government is looking to Parliament to provide directions in this regard, Khar said.

"We have no hostility towards any country and we want to be partners of the world in this effort," she said.

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(Agencies)