Organs from executed prisoners are used for transplants in China but only in "a very few cases" and with the express consent of the convicts, the government said today.

In a rare official admission that organs from people put to death are used for transplants, foreign ministry spokesman Qin Gang said it was a "lie" that China was forcing convicts to take part.

"This practice has taken place in a very few cases, and there is no difference between such cases and cases where a patient is going to die and donates his or her organs," he told a regular briefing.

"We have to go through strict formalities. So it's a complete fabrication and a lie when people say that China forcefully removes organs from people sentenced to death."

His comments addressed criticism that organs from executed prisoners are harvested to help overcome a major shortage in China's transplant system.

China executes more people a year than the rest of the world combined, according to Amnesty International.

The government maintains strict secrecy over the number of people it puts to death.

However Chinese academics have previously said that up to 10,000 people are executed each year, while rights groups say the number could be as high as 15,000.

Qin made the remarks shortly after the health ministry issued regulations to go into effect on July 1 banning the purchase and sale of organs, while also introducing a set of medical standards for transplants.

The problem took on an international focus early this year after reports that Japanese and Malaysians had died after travelling to China for organ transplants.

Qin told the briefing there had been no restrictions up to this stage on organ donations to foreigners.

"But in China if you engage in transplants, whether you want to receive or donate an organ, you have to go through strict formalities and follow strict regulations," he said.