Pakistani troops fire on US helicopters

Pakistani troops and tribesmen opened fire on two U.S. helicopters that crossed into the country from neighboring Afghanistan, intelligence officials said Monday. The U.S. denied the report.

The helicopters did not return fire and re-entered Afghan airspace without landing, the officials said, speaking on condition of anonymity because they were not authorized to speak to media.

"There was no such incursion, there was no such event," said Col. Gary L. Keck, Defense Department spokesman.

The reported incursion late Sunday will likely add to tensions between Islamabad and Washington.

A spate of suspected U.S. missile strikes into Pakistan's border region and a raid by U.S. commandos said to have killed 15 people have angered and embarrassed Pakistani leaders while signaling Washington's impatience with Pakistani efforts to clear out militant havens.

During a recent speech to Parliament, newly elected President Asif Ali Zardari, who is considered U.S.-friendly, warned that no country would be allowed to violate Pakistan's sovereignty in the name of the war on terror.