The officials said 12 soldiers were wounded in the attack late November 25 in the Mohmand Agency area, one of seven districts of the volatile region bordering Afghanistan. The death toll could rise as many of the injuries are critical, they said.

In a statement, Pakistani Prime Minister Yousuf Raza Gilani said he "strongly condemned the NATO/ISAF attack on the Pakistani post."

The matter is being taken up by the Foreign Ministry "in the strongest possible terms" with NATO and the United States, he said.

NATO has said it is aware of "an incident," but has not released any details.

Meanwhile, Pakistan has halted the flow of NATO supplies in Khyber Agency bordering Afghanistan in response to the attack, said Jamil Khan, a senior government official in the area.

About 50 containers and trucks carrying supplies for NATO were stopped at the town of Jamrud in Khyber Agency on November 26, Khan said.

A second route from Pakistan into Afghanistan, the Chaman border crossing inBalochistan province, is still open to NATO supply trucks.

Roughly 40% of nonlethal NATO supplies and fuel go through Pakistan, with hundreds of supply trucks using the two routes into Afghanistan.