China is selling the organs of thousands of its executed prisoners for transplants, alleges the British Transplantation Society, although Chinese officials deny it.

An accumulating weight of evidence suggests the organs of executed prisoners in China are being removed for transplants without consent, the society has alleged in a statement reported in the online edition of BBC News.

Professor Stephen Wigmore, who chairs the society’s ethics committee, said the speed of matching donors and patients, sometimes as little as a week, implied that prisoners were being selected before execution.

He said he and his colleagues had seen cases of British patients who had considered going to China for transplants.

Secrecy surrounding executions in China has always made it difficult to gather facts. In the statement released on Wednesday, the society condemned the practice as unacceptable and a breach of human rights.

The move comes less than a week after Chinese officials publicly denied the practice.

In March, China said it would ban the sale of human organs from July.

Chinese authorities recently announced that from July, selling organs would be illegal and all donors must give written permission.

But the practice is lucrative and critics say much will depend on how well those rules are implemented.