The Taliban has released a 28-minute video showing a US soldier reportedly captured by the hard-line Islamist group in Afghanistan last month, officials and witnesses said.

The clip released over the weekend shows a Western male -- purportedly a US soldier who went missing from his base in eastern Afghanistan on June 30 -- sitting 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 while drinking green tea.

Although the Pentagon has not released the identity of the missing soldier, a US military spokesman in Kabul confirmed that the man appearing in the video is the soldier who went missing late last month.

"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 questioner.

Asked 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."

"We're told that civilian casualties that soldiers like myself inflict on populous are simply something that we have to accept in a time of war and that we're told that they don't matter," the soldier adds.

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

The Kabul-based US military spokesman labelled the footage "propaganda."

"The US military condemns the release of this video by rebels," the 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.

Earlier Sunday US-based monitoring group IntelCenter said the video contained a production group logo that has been associated with Taliban-related videos in the past. This logo dates to at least August 2008, the group said.

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

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 elections next month.