U.S. forces said a U.S. and Afghan army patrol killed 35 militants in Zabul province, east Afghanistan, when the patrol''s convoy came under attack.

Violence has reached its highest levels in Afghanistan since the U.S.-led overthrow of the Taliban in 2001, and east Afghanistan, which borders Pakistan, is seeing an influx of U.S. troops as part of Washington''s 21,000 troop expansion.

"The Afghan-led force was conducting a combat reconnaissance patrol early this morning, when the convoy came under heavy fire from militants using small arms and mortar fire," said the statement, released late on Thursday.

The statement added that the patrol was being led by the Afghan army, which tends to be accompanied by U.S. military units tasked with mentoring and supporting the Afghan soldiers on operations and in battle.

The incident happened on the same day the U.S. military said American and Afghan troops killed 29 militants in neighboring Paktika province in a firefight in Wor Mamay district.