Islamabad — Relations between America and Pakistan were dealt a severe blow yesterday when American bombs killed 11 Pakistani soldiers.

The attack underscored distrust between the two countries that has deepened since they became allies in the American-led “war on terror” after the attacks of September 11, 2001. The strike, late on Tuesday, followed a clash between Afghan forces and Taliban militants in Kunar near the Pakistani Mohmand tribal area. Pakistan’s prime minister, Yusuf Raza Gilani, condemned the attack.

“The senseless use of air power against a Pakistani border post by coalition forces is totally unacceptable. It constitutes a blatant and wilful negation of the huge sacrifices that Pakistan has made in its endeavour to combat terrorism,” a Pakistani foreign ministry statement said.

A Pakistan army statement said the incident was a “completely unprovoked and cowardly act.” The chief army spokesman, Major General Athar Abbas, said that between 30 and 40 Afghan soldiers had tried to set up a post on a height above a Pakistani base in a “disputed area, a no-man’s land.” The Afghans were persuaded to return “amicably,” he said, but were engaged by insurgents one mile inside Afghan territory.

He said coalition air support provided to the Afghans targeted a nearby post housing members of the Pakistani paramilitary Frontier Corps. “We believe it was a deliberate act of aggression.”

An American military statement said the air and artillery raid was aimed at Taliban militants and had been “co-ordinated with Pakistan.” Communications between Afghan and American forces and their Pakistani counterparts are remarkably poor.

American officials have expressed concern that the Pakistani policy of striking peace deals with militants has led to a tripling of cross-border infiltration by militants from Pakistan.

A respected author and authority on the Taliban, Ahmed Rashid, said American military chiefs were furious because the Pakistani army is withdrawing from the tribal areas.

“The bulk of the Pakistan army will remain deployed on its eastern border and train for any possible threats from its traditional enemy, India,” he said. “There are also signs that Washington is delaying delivery of U.S. arms meant for the eastern front and is asking Western allies to do the same”

Disputes over the 1,500-mile frontier with Afghanistan have been provoked by previous American strikes on Pakistani border posts. Pakistan has protested over a series of missile strikes attributed to American-led forces in Afghanistan in recent months, including one in the tribal region of Bajaur last month that killed more than a dozen people.