ISLAMABAD (AP) - Afghanistan officials claimed Sunday that Afghan and NATO forces were retaliating for gunfire from two Pakistani army bases when they called in airstrikes that killed 24 Pakistani soldiers, adding a layer of complexity to episode that has further strained Pakistan's ties with the United States.
The account challenged Pakistan's claim that the strikes were unprovoked.
The attack Saturday near the Afghan-Pakistani border aroused popular anger in Pakistan and added tension to the U.S.-Pakistani relationship, which has been under pressure since the secret U.S. raid inside Pakistan that killed Osama bin Laden in May.
Pakistan has closed its western border to trucks delivering supplies to coalition troops in Afghanistan, demanded that the U.S. abandon an air base inside Pakistan and said it will review its cooperation with the U.S. and NATO.
A complete breakdown in the relationship between the United States and Pakistan is considered unlikely. Pakistan relies on billions of dollars in American aid, and the U.S. needs Pakistan to push Afghan insurgents to participate in peace talks.
Afghanistan's assertions about the attack muddy the efforts to determine what happened. The Afghan officials, who spoke on condition of anonymity because of the sensitivity of the issue, said it was unclear who fired on Afghan and NATO forces, which were conducting a joint operation before dawn Saturday.
They said the fire came from the direction of the two Pakistani army posts along the border that were later hit in the airstrikes.
NATO has said it is investigating, but it has not questioned the Pakistani claim that 24 soldiers were killed. All airstrikes are approved at a higher command level than the troops on the ground.
Secretary-General Anders Fogh Rasmussen offered his deepest condolences and said the coalition was committed to working with Pakistan to "avoid such tragedies in the future."
"We have a joint interest in the fight against cross-border terrorism and in ensuring that Afghanistan does not once again become a safe-haven for terrorists," Rasmussen said.
NATO officials have complained that insurgents fire from across the poorly defined frontier, often from positions close to Pakistani soldiers, who have been accused of tolerating or supporting them.
The U.S. plans its own investigation.