KABUL, Afghanistan — Two separate assaults on U.S.-led forces in Afghanistan killed 11 insurgents, a U.S. service member and an Afghan soldier, the U.S. military said yesterday.

The latest violence comes amid fears that crucial legislative elections in September may be threatened by an upsurge in attacks by Taliban holdouts that have left more than 750 people dead since March.

In fighting yesterday, insurgents attacked a patrol in southern Uruzgan province, setting off a gunbattle that killed the U.S. soldier, the Afghan soldier and the 11 insurgents, as well as wounding three U.S. troops and an Afghan soldier, a military statement said.

U.S. fighter jets and attack helicopters responded to the assault, the military said. Eight insurgents were captured.

"This tragic loss strengthens our resolve to further the advance of a democratic Afghanistan," said U.S. Army Brig. Gen. Jack Sterling, deputy commanding general of Combined Joint Task Force-76.

The death brings to 173 the number of U.S. troops killed in and around Afghanistan since Operation Enduring Freedom began in 2001. The latest death came a day after another U.S. service member was killed in a firefight in neighboring Helmand province.

On Sunday, a roadside bomb wounded six U.S. service members traveling in a convoy in eastern Kunar province. Insurgents then fired on the vehicles before fleeing when U.S. aircraft and artillery fired back, a separate U.S. military statement said. It was not immediately known whether any enemy fighters were killed or wounded, it said.

The attacks occurred in the same mountainous area where last month a commando team was ambushed, leaving three Navy SEALs dead, and a special-forces helicopter was shot down, killing all 16 troops on board.

Sunday's attack was the first major assault on U.S. forces in Kunar since then and may indicate that many of the insurgents thought to have fled across the border into neighboring Pakistan after the violence in June have sneaked back into Afghanistan.

Osama bin Laden and the reclusive Taliban leader Mullah Mohammed Omar are among those believed to be hiding along the Afghan-Pakistan border.

U.S. military officials and Afghan authorities, meanwhile, said they are investigating the authenticity of a cassette recording of a man claiming to be the fugitive Taliban chief.

Afghan Defense Ministry spokesman Gen. Mohammed Saher Azimi said the government suspects the recording is fake.

U.S. military spokesman Lt. Col. Jerry O'Hara said the armed forces do not have a copy of the recording but said the military was checking on it. The CIA declined to comment.

In a telephone interview with The Associated Press, purported Taliban spokesman Mullah Latif Hakimi played the tape, but the voice was garbled and unrecognizable. Hakimi then read out the comments.

"This cassette proves that I am alive and was not killed in bombings," Hakimi cited Omar as saying. "The leaders of the Taliban must unite and consult each other regarding the holy war. Our fight against the non-Muslims will be successful."

Hakimi said Omar made the recording in Afghanistan but declined to say when.

Information from Hakimi in the past has sometimes proved exaggerated or untrue, and his relationship to the Taliban leadership cannot be independently verified. Earlier this month, he claimed that one of the SEALs in the downed helicopter had been captured alive and beheaded. The U.S. military said the SEAL died in fighting.