A spokesman for NATO-led troops in Afghanistan confirms that NATO aircraft were called in to support troops during an incident near the border with Pakistan, and its forces were "highly likely" responsible for the deaths of at least 26 Pakistani soldiers.
Brigadier General Carsten Jacobson, spokesman for the NATO-led International Security Assistance Force (ISAF), said in Kabul that "close air support was called in, in the development of the tactical situation, and it is what highly likely caused the Pakistan casualties."
Islamabad has condemned the attack, with the chief of Army staff, General Ashfaq Pervez Kayani, demanding that "strong and urgent action be taken against those responsible for this aggression."
Pakistan's government also demanded that the United States vacate an air base within 15 days that the CIA is suspected of using for unmanned drones.
Pakistan has also stopped supplies to NATO forces in Afghanistan. Mutahir Hussain, a senior administration official in the Khyber tribal region, told AFP "we have stopped NATO supplies after receiving orders from the federal government."
The White House expressed its "desire to work together" with Pakistan to investigate the incident.
Secretary of State Hillary Rodham Clinton and Defense Secretary Leon Panetta in a joint statement said they had each spoken to their Pakistani counterparts to express their condolences for the loss of life.
NATO says it is looking into the incident. In Kabul, General Carsten Jacobson, a spokesman for the NATO-led International Security Assistance Force (ISAF), tells RFE/RL's Radio Free Afghanistan that the alliance is looking into the incident.
"We cannot confirm any numbers yet. We can confirm that we are aware of an incident on the border of Kunar and the border country. We are looking into that incident," Jacobson said.
An ISAF statement quoted coalition forces commander General John R. Allen as assuring his "highest personal attention" to thoroughly investigate the incident. "My most sincere and personal heartfelt condolences go out to the families and loved ones of any members of the Pakistan Security Forces who may have been killed or injured," he said.
Sources in Mohmand have told RFE/RL's Radio Mashaal that security forces were still looking for some missing troops in the region. Adil Sidiq, the top civilian official in the district, says that a large number of soldiers are deployed in the Baizai border region of the Mohmand tribal district to fight Taliban militants.
Influential Baizai tribal leader Malik Sultan says that tribal elders and young volunteers were helping the military to tend to the wounded and transport the dead from the remote region.
"The place where the attack happened is called Salala Dey Butanoo Sar. It borders the district of Ghoshta [in the eastern Afghan province of Nangarhar] and also adjoins the [eastern Afghan province] of Kunar," Sultan said.
"Tribal elders and volunteers have gone there to help with the ongoing rescue operation. The attack happened around midnight local time. No local civilians were targeted. Only a border post of the Pakistani military was hit."
The attack comes as relations between Washington and Islamabad are strained following the killing of Al-Qaeda leader Osama bin Laden by U.S. Special Forces in a secret raid on the Pakistani garrison town of Abbottabad in May.
"Prime Minister Yousuf Raza Gilani has condemned in the strongest terms the NATO/ISAF attack on the Pakistani post," Pakistani Foreign Ministry spokeswoman Tehmina Janjua said in a statement. "On his direction, the matter is being taken [up] by the Foreign Ministry in the strongest terms with NATO and the U.S."
The incident occurred a day after U.S. General John Allen met Pakistani Army Chief of Army Staff General Ashfaq Pervez Kayani to discuss border control and enhanced cooperation.
This raid is the largest and most serious incident of its kind. A similar incident on September 30, 2010, which killed two Pakistani troops, led to the closure of one of NATO's supply routes through Pakistan for 10 days.
NATO apologized for that incident, which it said happened after NATO gunships mistook warning shots by the Pakistani forces for a militant attack.
with agency reports