China will start phasing out the use of executed prisoners as a source of organs for transplants next year, a researcher for the government has said, according to a World Health Organisation magazine.

China will introduce a new organ donation system to "relinquish the reliance on organs from executed convicts," Wang Haibo, a senior researcher at China's Ministry of Health, told the November edition of the Bulletin of the World Health Organisation.

"An organ transplantation system relying on death-row prisoners' organs is not ethical or sustainable," Wang said, adding that the new system will be launched "early next year at the latest".

China has long vowed to reduce its reliance on death-row inmates for organs, but high demand and a chronic shortage of donations mean they have remained a key source -- a situation that has generated heated controversy.

Wang indicated that the reduction in the use of executed-prisoners' organs would be gradual, saying that the new system would require "phasing out the old practice".

Beijing banned the trade in human organs in 2007 and two years later began rolling out a nationwide donation system. But demand for organ transplants still far exceeds supply in the country of 1.3 billion people.

An estimated 1.5 million patients need transplants every year but only around 10,000 are carried out, according to official statistics, opening the door to the illegal sale of organs and forced donations.

Organ donations are not widespread in China, where many people believe they will be reincarnated after death and therefore feel the need to keep a complete body.

International human rights groups have long accused China of harvesting organs from executed prisoners for transplant without the consent of the prisoner or their family -- accusations the government has denied.

In 2009 a health ministry spokesman said the rights of death-row inmates were respected and written consent from prisoners was required before their organs could be harvested, state media said at the time.

China executed around 4,000 prisoners last year, a 50 percent drop since 2007, according to US-based advocacy group the Duihua foundation.