WASHINGTON NATO forces may have been lured into attacking friendly Pakistani border posts in a calculated manoeuvre by Taliban, according to preliminary US military reports on the deadliest friendly fire incident with Pakistan since the Afghanistan war began. The NATO airstrike killed 24 Pakistani soldiers over the weekend in an apparent case of mistaken identity, an American news agency has learned. A joint US-Afghan patrol was attacked by the Taliban early Saturday morning. While pursuing the enemy in the poorly marked border area, the patrol seems to have mistaken one of the Pakistan troop outposts for a militant encampment and called in a NATO gunship and attack helicopters to open fire. US officials say the reports suggest the Taliban may have deliberately tried to provoke a cross-border firefight that would set back fragile partnerships between the US and NATO forces and Pakistani soldiers at the ill-defined border. Officials described the records on condition of anonymity to discuss classified matters. The incident has sent the perpetually difficult US-Pakistan relationship into a tailspin. According to the US military records described to the news agency, the joint US and Afghan patrol requested backup after being hit by mortar and small arms fire by militants. Before responding, the joint US-Afghan patrol first checked with the Pakistani Army, which reported it had no troops in the area, the military account said. Some two hours later, still hunting the insurgents who had by then apparently fled in the direction of Pakistani border posts the US commander spotted what he thought was a militant encampment, with heavy weapons mounted on tripods.