KABUL (Reuters) -- Two U.S. soldiers and an Afghan soldier were killed in a clash with insurgents in the eastern Afghan province of Kunar, the U.S.-led coalition force said on Tuesday.

Three U.S. soldiers were also wounded in the fighting late on Monday in the province's Pech district.

Violence has surged in the Afghan east and south this year to its most intense since U.S.-led forces ousted the hardline Taliban five years ago, weeks after the Sept. 11 attacks.

"The soldiers were operating as part of a combat patrol that made contact with enemy extremists," the U.S. military said. "The unit engaged the insurgents with small arms and artillery fire," it said. It did not identify the soldiers killed or wounded.

A NATO-led force is due to take command of Afghanistan's eastern provinces from the U.S.-led coalition force in coming days. The 10,000-12,000 U.S. troops now based in the east will come under NATO command.

NATO took over from the U.S.-led coalition in the south at the end of July. Its troops, in particular British and Canadians, have come up against fierce Taliban opposition.

NATO has about 20,000 troops in Afghanistan and the United States has a similar number.

About 140 foreign troops have been killed in violence or accidents during operations in Afghanistan this year, most of them Americans, Canadians and British.

The violence has raised concerns for Afghanistan's prospects and some opposition to Afghan involvement among the public and opposition parties in some NATO members.

But Western governments say they are fully committed to ensuring Afghanistan's security.