KANDAHAR, Afghanistan — A purported Taliban spokesman said yesterday that the group has beheaded a missing American commando, but he offered no proof and the U.S. military said it was still searching for the Navy SEAL.

The commando is the last of a four-member elite commando team missing since June 28 in Kunar, near the Pakistani border. One of the men was rescued and the other two — including Petty Officer 2nd Class Shane Patton, a Pearl Harbor-based Navy SEAL — were found dead.

"This morning in Shagal district in Kunar province, the Taliban killed the American soldier and cut his head off," Mullah Latif Hakimi, the purported spokesman, said. "We left the body on a mountainside in this area so Afghan or U.S. soldiers there can find it."

Hakimi repeatedly has said the rebels were holding the commando, but information from him in the past has frequently proven exaggerated or untrue, and his exact tie to the Taliban leadership cannot be independently verified.

U.S. military spokesman Lt. Col. Jerry O'Hara said the search for the commando was continuing.

"The only proof we have is that he is missing," he said. "We will run down these reports to see if anything pans out."

About 300 troops and several aircraft have been searching for the U.S. Navy SEAL in the rugged mountains in eastern Afghanistan, the military has said.

When asked for evidence of the commando's death, Hakimi said, "the proof will be when the Americans find his body."

Hakimi said earlier this week that the rebels would release a video, but he made no mention of that yesterday.

The Navy SEAL team went missing after a special forces Chinook helicopter carrying reinforcements to the mountainous area was shot down, killing all 16 Americans on board, the deadliest single attack on the U.S. military since the war here began in 2001.

Three Pearl Harbor SEALs were aboard the Chinook, bringing to four the number of Hawai'i-based troops involved in the original mission and subsequent rescue operation.

The 16 troops on the helicopter were responding to a call for help from the four SEAL commandos on reconnaissance in the rugged Afghan mountains who were attacked by militants.

Kunar province has long been a hotbed of militant activity and a haven for fighters loyal to renegade former premier Gulbuddin Hekmatyar, who is wanted by the United States. U.S. officials said al-Qaida fighters also were in the region. Osama bin Laden was not said to be there — though he is believed to be somewhere along the Afghanistan-Pakistan frontier.

The region's wooded mountains are popular with militants because they are easy to infiltrate from neighboring Pakistan and have plenty of hiding places.

On July 2, a U.S. air strike in the region killed as many as 17 civilians, prompting a strong rebuke from the Afghan government.

The violence follows an unprecedented spate of insurgent fighting that has left about 700 people dead and threatened to sabotage three years of progress toward peace. Afghan officials insist the violence will not disrupt landmark legislative elections slated for September.

In the latest violence, suspected Taliban gunmen ambushed a border patrol in the desert near Pakistan, killing 10 Afghan soldiers and beheading them all, a provincial governor said today.

The victims were part of a 25-member patrol in southern Helmand province that was attacked late yesterday by militants, said provincial Gov. Sher Mohammed Aghunzada.

"The Taliban cut the heads off all the soldiers who were killed," he said. Aghunzada said the dead soldiers' bodies had been recovered.

Also, suspected rebels shot to death a senior pro-government cleric and his wife in eastern Paktika province Thursday, Gov. Gulab Mungle said. Four suspects have been arrested, he said.

Correction: Petty Officer 2nd Class Shane Patton, 22, of Boulder City, Nev., was one of three Pearl Harbor-based SEALs killed when their helicopter was shot down during a rescue mission in Afghanistan on June 28. Lt. Michael P. Murphy, 29, of Patchogue, N.Y., also a Pearl Harbor-based SEAL, was part of a four-man commando team that disappeared June 28 in Kunar Province in Afghanistan. A previous version of this story contained incorrect information.