Pakistan's army on Wednesday accused the US-led coalition of killing 11 Pakistani paramilitary troops in an air strike along the volatile Afghan border. The strike late Tuesday followed a reported clash between Afghan forces and Taliban militants in the same area. The Taliban said that eight of its fighters died in the skirmish. A Pakistan army statement said the incident late Tuesday in Pakistan's Mohmand tribal region "had hit at the very basis of cooperation" between the two countries in the war on terror. The army has launched a strong protest and reserved "the right to protect our citizens and soldiers against aggression," it said. In Washington, a Pentagon official said there was an air strike Tuesday night during an incursion by insurgents into Afghanistan from Pakistan. Coalition forces responded to the attack, and during the battle there was at least one air strike, he said, noting that information on the incident was still sketchy. He spoke on condition of anonymity as he was not authorized to speak on the record. He said that initial reports indicated that during the firefight the insurgents fled and were pursued by two US aircraft. The aircraft launched an air strike under a policy that allows coalition forces to continue over the border with Pakistan if they are in hot pursuit of a target, he said. Other defense officials in the United States referred calls to the US Embassy in Pakistan, saying the subject was very sensitive, however the embassy declined to comment. The lawless and remote mountain region is difficult for reporters to access and there were conflicting reports over the sequence of events and how many died in the fighting. The region is believed used by pro-Taliban militants as a launch pad for attacks into Afghanistan. Infiltration is a constant source of tension in the counter-terrorism alliance. Pakistan has deployed tens of thousands of troops to police its tribal regions, but Western and Afghan officials said that it has not deterred militants. Afghanistan often accuses Pakistan of abetting the Taliban, whose hardline regime it supported until its ouster in 2001 for harboring al-Qaida. Pakistani officials said the fighting broke out Tuesday after Afghan troops tried to set up a mountaintop post in a contested part of the lawless frontier and Pakistani security forces told them to withdraw. Local tribesman Damagh Khan Mohmand said the Afghan forces had moved into the area around Speena Sooka, or White Peak, on Monday evening and were supported by foreign troops. There was no confirmation of that from the US-led coalition or NATO security force in Afghanistan. Khan Mohmand said tribesmen traded fire with the Afghan and foreign forces, and that Pakistani security forces also opened fire - although the military disputed that. The army said the coalition air strike hit a post of the paramilitary Frontier Corps and was a "completely unprovoked and cowardly act." Khan Mohmand said he saw drones and that two aircraft had bombed several locations. Maulvi Umar, a spokesman for an umbrella group of Pakistani Taliban, claimed that militants had resisted an incursion into Pakistan. He said between 60 and 100 of its fighters attacked NATO and Afghan army troops who had set up bunkers and tents on Pakistani soil. He claimed up to 40 Afghan troops were killed, several captured and that a NATO helicopter was shot down. Eight Taliban troops also died in the fighting, he said. None of his claims could be independently confirmed. State-run Pakistan Television said 18 people died in the fighting, including 10 troops and eight civilians. It reported that Afghan and foreign forces had tried to set up a military post and were resisted by tribesmen. A NATO air strike then struck a Pakistani military post, PTV said. Officials in Afghanistan declined comment. On Wednesday, two helicopters brought the bodies of 11 troops killed and another 13 soldiers wounded in the fighting to Peshawar, the main city in northwestern Pakistan, a military intelligence official said on condition of anonymity because he is not allowed to comment to media. Witnesses said seven ambulances shifted the casualties to a military hospital in the city. North West Frontier Province Gov. Owais Ahmed Ghani told reporters later at a funeral ceremony for the troops that such an attack "can compel us to review our policy (in the war on terror)." Anti-US sentiment is already running high in Pakistan, where the newly elected civilian rulers, particularly in that northwestern province, are seeking to broker peace with militants to curb an explosion in extremist violence. That marks a shift from former army strongman President Pervez Musharraf's greater reliance on military force. Western officials are concerned that peace deals could give Taliban and al-Qaida militants more space to operate. The United States has in the past used unmanned drones to attack suspected militants inside Pakistan. Pakistan said it does not allow foreign troops to conduct military operations on its territory, and that aerial attacks launched from Afghanistan are a violation of its sovereignty.