The Pakistani army has rejected a U.S. investigation that concluded mistakes on both sides led to U.S. air strikes last month that killed 24 Pakistani soldiers and severely damaged the already strained relationship between the two countries.

The response indicates the report will do little to ease tensions, a worrying development for the U.S. because Pakistan's co-operation is critical for its conduct of the Afghan war. The Pakistani army has said its troops did nothing wrong and claimed the attack was a deliberate act of aggression.

Pakistan has retaliated by closing its Afghan border to supplies meant for NATO troops in Afghanistan and kicking the U.S. out of a base used by American drones. NATO officials have said the closure of the supply route has not affected operations so far, but will eventually if not reversed.

The Pakistani Army said it "does not agree with the findings of the U.S./NATP inquiry as being reported in the media", in a short statement on Friday. "The inquiry report is short on facts," it added.

The army would provide a detailed response after officials received the report, it said. Pakistan refused to co-operate in the investigation.

Even though U.S. officials on Thursday accepted some of the blame for the attack on two army posts along the Afghan border and expressed regret for the deaths, they did not apologize for the incident, as many Pakistanis have demanded. Instead, the U.S. said its forces were fired on first from the direction of the posts and acted "with appropriate force" in self-defense.