Khar told the US National Public Radio that even if the Nov 26 airstrike was a mistake, “its certainly a callous mistake because this did not happen over five minutes.
“This was into hours, for sure, and that leaves many, many unanswered questions,” she said in Lahore.
NATO helicopter gunships opened fire at two Pakistani Army checkposts, killing two dozen soldiers and causing an outcry in the country. Islamabad promptly cut-off the passage of NATO supply through the country and also decided to boycott next week’s Bonn conference on Afghanistan.
Khar said the NATO attack is not an isolated incident and has raised much bigger questions than whether Islamabad will join an investigation into the event, Associated Press of Pakistan reported.
"I think the questions raised in Pakistan are much larger than whether we will participate in the investigation or not. I want to emphasize on the fact that this is not an isolated incident," she said.
The foreign minister said that the unilateral raid on Abbottabad raised questions about the red lines that Pakistan has put in place while cooperating with the international community in the anti-terror fight.
US commandos onboard stealth helicopters had swooped into Abbottabad and killed Al Qaeda leader Osama bin Laden May 2.
Khar said: "If the terms of engagement are not clearly understood, are not clearly respected, that gives each of the parties the right to go back and reassess the situation that I think Pakistan is, today, just exercising that right."
Pakistan, the foreign minister said, feels its role in the decade-old fight against terror has been "misinterpreted, has not been recognized, has not been appreciated enough".
"And, on top of that, to have an incident in which we feel, at best, giving the benefit of doubt, our soldiers lost their lives to an extremely callous attitude. This episode has obviously created a lot of rage in Pakistan because this is not the first time that Pakistan has lost its soldiers to NATO fire."
While Pakistan would like to wait for detailed investigations, the current briefings "seem to be pointing towards a direction which is not a happy case to be in", Khar said a question whether the NATO strike was deliberate.
"If it is a deliberate attempt, then the questions that I referred to would obviously be much, much, much more serious," she added.
To another query, she said: "I’m not going to run to any conclusion and I hope that is not true, but the fact of the matter is that even if it is a mistake, its certainly a callous mistake because this did not happen over five minutes. This was into hours, for sure, and that leaves many, many unanswered questions.”