The American military has briefed Pakistan's army chief on its investigation into US air strikes that killed 24 Pakistani soldiers on the Afghan border last month, US officials said Tuesday.

Pentagon spokesman Captain John Kirby told reporters that a report by military investigators was delivered to General Ashfaq Kayani on Sunday by a US officer based in Islamabad, who explained the findings to the general.

The full report from the joint US-NATO investigative team was not released publicly until Monday to allow time for the Pakistani leadership to read the findings first, Kirby said.

"We wanted General Kayani to be able to see the entire thing," he said, calling the approach "an appropriate professional courtesy" to Kayani.

But a Pakistani security official told AFP "no such briefing took place and the report was not handed over in person to the army chief".

"The report was delivered to the concerned department (of army headquarters) but not to the chief," the official said.

Pakistan has yet to give a detailed public response to the report, but officials have expressed irritation that elements were initially leaked to American newspapers last week.

The air strikes further damaged the precarious US-Pakistani partnership and provoked outrage in Islamabad, which retaliated by cutting off NATO supply routes to Afghanistan.

The New York Times has reported the counter-terrorism partnership can only survive in limited form.

The United States and Pakistan disagree about the precise sequence of events in the deadliest single cross-border attack of the 10-year war in Afghanistan.

Pakistan denies shooting first, and has accused the Americans of an intentional attack on its troops.

Brigadier General Stephen Clark, who led the US inquiry, said the November 25-26 air strikes were the result of mistakes and botched communications on both sides -- reflecting an underlying mistrust between the two countries.

It took the NATO-led force 84 minutes to halt air strikes after a Pakistani liaison officer first alerted US and coalition counterparts that Pakistani troops were coming under fire from American aircraft, the report said.

The probe also said the US military failed to notify the Pakistanis about the night raid near the border and that a coalition officer mistakenly gave the wrong location of the US troops to his Pakistani counterpart.

The probe found Pakistani soldiers fired first at American and Afghan forces and kept firing even after a US F-15 fighter jet flew overhead. The Pakistanis also failed to tell the Americans about new border posts in the area.