The Taliban have released a video showing a visibly-shaken captive US soldier reportedly snatched by the militants in Afghanistan last month, officials and witnesses said on Sunday.

In the 28-minute clip posted on the Internet at the weekend, the soldier who went missing in eastern Afghanistan on June 30, sits cross-legged on the floor wearing a traditional Afghan outfit.

The shaven-headed young man, who sports a small beard and appears nervous and frightened, answers questions in English, occasionally choking back sobs as he tells his captors he is scared and wants to see his family.

A US military spokesman in Kabul confirmed the man was the soldier who went missing in Paktika province late last month and condemned the video as "propaganda." The Pentagon has not yet released his identity.

"I was captured outside of the base camp. I was behind a patrol, lagging behind the patrol and I was captured," the soldier tells an unseen captor.

Questioned about the US-led invasion that toppled the hardline Taliban government in 2001, the man replies: "Since I've been here and I've seen how these people live and function, we have indeed invaded an independent state."

Asked if he has a message for his compatriots, the man says that they have the power to get troops out of Afghanistan.

"Please bring us home so we can be back where we belong and not over here wasting our time and our lives," he says.

Eating food and drinking green tea as he sits in front of a table, the man says the hard-line Taliban Islamists are "really treating me like a guest," but becomes distraught when talking about his family.

"I'm afraid that I might never see them again and that I'll never be able to tell them that I love them again, I'll never be able to hug them," he says.

"I'm scared... scared about not being able to go home. It's very unnerving to be a prisoner," the troop adds.

The man's military dog tags are shown to the camera, with his name visible. A link to the clip was sent to AFP by Taliban spokesman Zabihullah Mujahed early Sunday, and has now been posted on a number of websites.

"The US military condemns the release of this video by rebels," a Kabul-based US military spokesman, who requested anonymity, told AFP.

"They're exploiting the soldier for their own propaganda. US and coalition forces are doing everything they can to recover the soldier and get him back unharmed. The Taliban are using it as a propaganda tool," he added.

Hundreds of US soldiers and troops from other nations have been killed in Afghanistan battling the widening Taliban-led insurgency.

But the June 30 abduction is believed to be the first time militants have snatched an American soldier in Afghanistan since the war began in 2001.

A commander of the Taliban's Al-Qaeda-linked Haqqani faction on July 2 claimed the abduction, and the American military acknowledged that a soldier went missing after leaving his base for unexplained reasons.

The Taliban are the main militant group behind an increasingly deadly insurgency which they launched shortly after they were toppled from government.

The violence has reached new highs in recent weeks as thousands of US, British and Afghan troops launched a major assault against the rebel strongholds in the south ahead of national elections next month.