The Afghan Taliban released a video on Wednesday showing an American and an Australian hostage asking their governments to help negotiate a prisoner exchange with their captors to secure their release.

Kevin King, a teacher at the American University in Kabul, and his Australian colleague Timothy Weeks were seized near the campus in August last year.

The video, which King and Weeks said was made on June 16, showed the two men addressing the camera and asking for Taliban prisoners to be handed over in exchange for their freedom.

The video, whose authenticity could not be independently verified, was distributed by the Taliban's main spokesman and circulated on social media sites.

It follows a similar video of the two men which the Taliban released in January and comes as U.S. authorities are preparing their new strategy for Afghanistan, expected to include an increase of between 3,000-5,000 troops.

In September, the Pentagon said U.S. forces mounted a raid to try to rescue two civilian hostages but the men were not at the location targeted.

Kidnapping has been a major problem in Afghanistan for many years. Most victims are Afghans and many kidnappers are criminal gangs seeking ransom money but a number of foreigners have also been abducted for political ends.