Pakistani authorities blocked the vital supply route for NATO troops fighting in Afghanistan on Saturday after a cross-border air strike killed 25 Pakistani troops, local officials said.
Trucks and fuel tankers were stopped at Jamrud town in the Khyber tribal region near the city of Peshawar, hours after the raid, officials said.
“We have halted the supplies and some 40 tankers and trucks have been returned from the check post in Jamrud,” Mutahir Zeb, a senior government official, told Reuters.
Another official said the supplies had been stopped for security reasons.
NATO helicopters from Afghanistan carried out an “unprovoked” attack on a Pakistani border post on Saturday.
In Kabul, a spokesman for NATO’s International Security Assistance Force (ISAF) told AFP: “We are aware that an incident did take place. We are still in the process of gathering information.”
Pakistani security and military officials in the Mohmand tribal region, which is near the Afghan border, said an army major was among the killed in the pre-dawn incident.
A military spokesman said: “ISAF/NATO helicopters carried out unprovoked and indiscriminate firing on a Pakistani checkpost in Mohmand agency last night (early Saturday).”
The border post was in the Baizai district of the rugged tribal terrain.
Washington considers the tribal belt a hotbed of al-Qaeda, where Taliban and other militants plot attacks on American troops -- including those in the U.S.-led international force based in Afghanistan.
Masood Kausar, Governor of the northwestern Khyber Pakhtunkhwa province, strongly condemned the apparent NATO firing, calling it unacceptable.
In a statement he said the incident in which “eight Pakistani soldiers were martyred” was a violation of Pakistan's “sovereignty.”
“Such cross-border attacks are unacceptable and intolerable,” he said, adding the government would take up the matter at the highest level and launch a thorough investigation.
Pakistan-U.S. ties deteriorated sharply this year over a unilateral American raid that killed Osama bin Laden in May and over accusations that Pakistani intelligence was involved in a September siege of the U.S. embassy in Kabul.
U.S. officials say Pakistan’s tribal belt provides sanctuary to Taliban fighting for 10 years against U.S. troops in Afghanistan and Pakistani Taliban who routinely bomb Pakistan.
At talks in Islamabad last month, U.S. Secretary of State Hillary Clinton called on Pakistan to take action within “days and weeks” on dismantling militant havens and encouraging the Taliban into peace talks.