KABUL, Afghanistan – U.S.-led troops backed by warplanes battled militants in southwestern Afghanistan, killing 28 rebels including several Taliban leaders, an Afghan official said Monday.

Other reported violence claimed the lives of two Afghan soldiers, two militants and a government employee, while the Pentagon said a bomb killed an elite U.S. soldier last week.

Fighting between insurgents and security forces is escalating, damping the prospect of the Western-backed effort to stabilize the country succeeding any time soon.

The violence has killed more than 2,000 people so far this year, according to an Associated Press tally.

In the bloodiest of the latest incidents, the U.S.-led coalition said its troops came under fire Sunday in the Khash Rod district of Nimroz province as they searched compounds for a Taliban leader suspected of involvement in suicide attacks.

The troops killed “multiple militant groups” with small-arms fire, and airstrikes killed two more groups of attackers, the coalition said. There were no coalition casualties, it said.

While the coalition said only that “several” militants died and another was detained, Nimroz Gov. Ghulam Dastagir Azad said 28 rebels were killed. He said some of the victims were torn apart in the late-night bombing, making the body count difficult.

Azad said local officials had told him that four civilians also died.

His account could not be independently verified.

The governor said the slain militants included three Taliban commanders, each of whom controlled a group of some 40-50 fighters. He said they were suspected of targeting road construction crews with bombs and planning attacks on food relief convoys.

The U.N. reported Sunday that one of its relief convoys was attacked on its way to Nimroz and neighboring Helmand province, and that several trucks were burned. Other convoys have been looted.

Elsewhere, the Afghan Ministry of Defense said it lost two soldiers to a roadside bomb in the Zurmat district of Paktia province on Monday. Three more soldiers were wounded. The two militants were killed in a clash with Afghan soldiers in Helmand province, it said.

In Logar province, just south of the capital, officials said militants attacked the government office in the town of Azra on Monday morning, killing one civilian employee and wounding three police.

The American special forces soldier was fatally wounded by a bomb during a patrol on June 27, the Department of Defense said. The coalition said the incident occurred in Ghorak, a district of the southern province of Kandahar.