China's hospitals are harvesting the body parts of thousands of political prisoners and removing their vital organs while they are still alive, according to a harrowing documentary exposing the horrific state-sanctioned practice.

Doctors and medical students working in state-run civilian and military hospitals take up to 11,000 organs a year from donors under no anaesthetic to supply China's lucrative "organs on-demand" transplant program, say a network of invesitgators comprised of international researchers, doctors and human rights lawyers attempting to end the macabre abuses.

Human rigts lawyer David Matas has spoken out about organ harvesting in China.

The documentary, Human Harvest: China's Organ Trafficking, by Canadian filmmaker Leon Lee, followed these investigators for eight years as they worked to mobilise international condemnation of what they say is a booming billion-dollar organ harvesting industry for the benefit of wealthy paying organ recipients.

"When I cut through [the body] blood was still running ... this person was not dead," said one doctor of his first encounter with live organ harvesting as a medical student filmed by Lee.