Islamabad has so far refused to take part in a US inquiry into air strikes that killed 24 Pakistani soldiers, exacerbating fears Saturday of a prolonged US-Pakistani crisis as a result of the attack.
Pakistan was invited to cooperate in the probe into the November 26 strikes on the Afghan border, which enraged Islamabad and propelled US-Pakistani ties to their rockiest in years, but officials have declined to do so.
"They have elected to date not to participate, but we would welcome their participation," said Pentagon press secretary George Little.
Washington had expected a refusal given the fury in Pakistan, which has already seen Islamabad shut down NATO's vital supply into Afghanistan and boycott an international conference on the war in Bonn set for Monday.
Pakistan also ordered American personnel to leave the Shamsi air base, widely understood to have been a hub for a covert CIA drone war on Taliban and Al-Qaeda commanders in Pakistan's troubled border areas with Afghanistan.
In Pakistan, a security official told AFP on condition of anonymity Saturday that a formal reply would be conveyed to the Americans, but confirmed there was no interest in taking part in the inquiry.
"Officially our response has yet to come, but we will not participate in the investigation because there was no outcome from the two previous inquiries and we feel that third inquiry will be the same, so there's no purpose," he said.
Pakistan claims NATO attacks in 2010 and 2008 were poorly investigated.
On Friday, the Wall Street Journal quoted US officials as saying Pakistani officers at a coordination centre gave a green light for the strikes believing they had no troops in the area.
But a Pakistani official told AFP that the Americans relayed the wrong coordinates, instead for a site 15 kilometres (nine miles) to the north.
"This is totally ridiculous," he said on condition of anonymity, because he was not authorised to speak to the media.
"They thought there is some activity in that particular area... We confirmed there was no activity in that area. After some time, the same border coordination centre said we're sorry it's the wrong coordinates," he added.
Pakistan says there was then a second air strike.
"The first strike could have been a mistake. They pulled out. What was the purpose of coming again? That is the most disgusting thing," the official said.
US officials told the Wall Street Journal that Afghan forces and US commandos were pursuing Taliban fighters near the border when they came under fire from what they thought was a militant encampment.
But it also quoted officials as saying there were mistakes on both sides: "There were lots of mistakes made," one official said. "There was not good situational awareness to who was where and who was doing what."
The United States has voiced regret over the strikes but has stopped short of issuing an apology while the American military conducts the investigation.
"It's safe to say that the incident has had a chilling effect on our relationship with the Pakistani military, no question about that," Pentagon spokesman Captain John Kirby told reporters in Washington.
"Both sides deem it to be as serious as it was."
Pakistan called the strikes a "deliberate act of aggression" and army chief General Ashfaq Kayani is understood to be facing fury from the ranks and junior officers livid with the Americans.
Kayani told troops to respond to any future attack without waiting for approval from commanders in what local media interpreted as a change in the rules of engagement.
Kirby suggested the US military would also review its operations and tactics for forces stationed in eastern Afghanistan.
"Clearly, an incident like this causes you -- and should cause you -- to take a step back and look at how you're doing things and whether there need to be improvements made or any kind of tactical decisions ...(to) do things a little differently," Kirby said.