Pakistan on Monday denied reports that its troops opened fire first, therefore triggering lethal Nato cross-border air strikes that left 24 Pakistani soldiers dead.
"This is not true. They are making up excuses. And by the way, what are their losses, casualties?" Major General Athar Abbas, Pakistan's chief military spokesman, wrote to AFP in a text message.
The Wall Street Journal, citing three unnamed Afghan officials and one Western official, said Saturday's attack, which has prompted fury in Islamabad, was called in to shield Nato and Afghan forces targeting Taliban fighters.
The fire came from remote outposts in the Mohmand region in Pakistan's lawless tribal belt, branded an al Qaeda hub by Washington.
An Afghan official said that the government in Kabul believes the fire came from a Pakistani military base -- and not from insurgents in the area.
That version was corroborated by two Afghan officials working in the border zone. One border police official said Pakistani officials were informed of the Nato operation ahead of time, the Wall Street Journal said.