U.S. forces desperately scoured rugged Afghan mountains Friday for an elite American military team missing in the same area where a U.S. helicopter was shot down.

A purported Taliban (search) spokesman claimed militants captured one of the men.

In central Afghanistan (search), Taliban rebels kidnapped and killed nine Afghan tribal leaders and sent a boy to offer to exchange the bodies for those of dead militants, an official said. The tribal leaders were among 25 people killed in three days of fighting in Uruzgan province — yet another troubling sign for a nation hit by an upswing in violence as September elections near.

The loss of the American military team in the remote eastern mountains worsened the already stinging blow suffered by the U.S. military after 16 troops were killed Tuesday aboard the MH-47 Chinook chopper (search).

It comes as the United States is scrambling to deal with an insurgency that threatens three years of progress toward peace.

U.S. forces were using "every available asset" to search for the missing men, U.S. military spokesman Lt. Col. Jerry O'Hara said.

"Until we find our guys, they are still listed as unaccounted for and everything we got in that area is oriented on finding the missing men," he said.

The missing troops are a small team from the special operations forces, said military officials, speaking Friday on the condition of anonymity because rescue operations were still under way.

Though the team has been missing since Tuesday, the military had refrained from discussing their situation to prevent the Taliban from setting out in search of them.

The downed helicopter had been trying to "extract the soldiers" Tuesday when it went into the mountains near Asadabad, close to the Pakistani border, O'Hara said.

The Taliban claim to have kidnapped one of the men came from purported spokesman Mullah Latif Hakimi. "One high-ranking American has been captured in fighting in the same area as the helicopter went down," he told The Associated Press. "I won't give you any more details now."

Reacting to the claim, O'Hara said, "We have no proof or evidence indicating anything other than the soldiers are missing."

Hakimi, who also claimed insurgents shot down the helicopter, often calls news organizations to take responsibility for attacks, and the information frequently proves exaggerated or untrue. His exact tie to the Taliban leadership is unclear.

At the Pentagon, Lt. Gen. James Conway, director of operations for the Joint Chiefs of Staff, said the military did not yet have a full account of all ground troops involved in the operation, but he said no one had been classified as officially missing.

Rescuers — struggling against stormy weather, insurgents and the rugged terrain — recovered the remains of the 16 and were trying to identify them, the military said. A rocket-propelled grenade appears to have hit the chopper, Conway said, calling it "a pretty lucky shot."

The loss of the helicopter follows three months of unprecedented fighting that has killed about 477 suspected insurgents, 47 Afghan police and soldiers, 134 civilians, and 45 U.S. troops.

In Uruzgan province, violence erupted when insurgents attacked a police checkpoint and an hour-long gunbattle left seven rebels dead Wednesday, provincial Gov. Jan Mohammed Khan said.

On Thursday, the militants assaulted a nearby village in retaliation, kidnapping nine tribal elders and a 10-year-old boy, he said.

The elders later were killed and the boy sent to the authorities with a message: If police hand over the bodies of the seven militants, the insurgents will release the bodies of the nine, Khan told The Associated Press.

The police did not respond to the offer. "We have started operations and we are going to hunt them down," the governor said.

On Friday, rebels attacked another Uruzgan police post, and five insurgents and four officers were killed, Khan said.

Only eight months ago, Afghan and U.S. officials were hailing a relatively peaceful presidential election as a sign that the Taliban rebellion was finished.

But remnants of the former Taliban regime have stepped up attacks, and there are disturbing signs that foreign fighters — including some linked to al-Qaida — might be making a new push to sow an Iraq-style insurgency.

Afghan officials say the fighters have used the porous border with Pakistan to enter the country, and officials have called on the Pakistani government do more to stop them.