KABUL, Aug 3: Afghan troops backed by American soldiers and warplanes may have killed up to 50 militants in a day-long pitched battle at a southeastern border post near Pakistan, the US military said in a statement.

"The exact number of enemy casualties is unknown but pilots flying overhead estimated that approximately 40 to 50 insurgents were killed," the statement said. One Afghan soldier was killed and three were wounded, it added. The battle was among the heaviest since the Taliban regime was ousted.

Clashes erupted before dawn on Monday at a border post between Khost province and Pakistan's western tribal region. About 50 suspected Taliban insurgents attacked the post at 2am on Monday (2130 GMT Sunday) with rocket-propelled grenades, machineguns and mortars.

US air forces flew in B-1 bomber, A-10 Thunderbolt aircraft and attack helicopters to repel the insurgents, who "retreated in panic" at the sight of the fighter craft, the military said. Five hours later the fighting broke out again and raged into Monday night. -AFP