Islamabad/Washington:  Pakistan and US find themselves at odds with each other again with Islamabad rejecting the American probe into the deadly NATO cross border strike that left 24 Pakistani soldiers dead and Washington standing by it "100 percent".

The first salvo was fired by the Pakistan Army which on Monday officially rejected the probe report of the November 26 attack prepared by American Brigadier General Stepehen Clark saying Islamabad does not agree with several portions and findings of the 'Investigation Report' as these are not factually correct.

The Pakistan Army also argued that the NATO strike was an "unprovoked attack".

Hours later, the Pentagon struck back saying US stands by its own investigation that it was not an unprovoked firing by the US-led forces.

"This (Pakistan military remarks) does not change our believes in the validity of the findings. The statement that this was an unprovoked attack by American forces is simply false," Pentagon spokesman Navy Capt John Kirby said.

Asserting that the US stands "100 per cent" by the investigation done by a top general from the Central Command (CENTOCM) released last month, Kirby said the US had desired Pakistani participation in that investigation, which then would have been more thorough.

Pakistan's absence from participation in the CENTCOM investigation, Kirby said: "does not change our firm believe in the validity of the findings of the investigations that we did".

The Pakistani army which had issued a statement on Monday rejecting the probe report, have also uploaded a detailed "Pakistani Perspective on the US Investigation Report", approved by Pakistan's Defence Committee of the Cabinet, on its media arm ISPR's website.

Saying that it has received the unclassified version of the probe report, Pakistan has demanded that "full and complete classified version of the US Investigation Report be made available."

It has also sought provision of Intelligence Surveillance and Reconnaissance picture of the complete incident along with all aerial platform videos and record of radio transmissions and communication between the crew(s) of the aerial platforms involved in the incident.

The NATO strike was a huge setback to the then already tense US-Pak relations.

Pakistan had reacted angrily after the soldiers were killed and 13 more injured when NATO helicopters and combat jets from Afghanistan targeted two military check posts in Salala area of Mohmand tribal region.

Islamabad shut down all NATO supply routes and forced the US to vacate Shamsi airbase, which was reportedly used by CIA-operated drones.

Prime Minister Yousuf Raza Gilani announced shortly after the attacks that it could not be "business as usual" between Pakistan and the US.

Acting on Gilani's instructions, a parliamentary committee has framed over 30 recommendations for the revamp of bilateral relations.

A joint session of the Parliament is expected to debate these recommendations next month.