 In December 2006, after not getting assurances from the Chinese government about allegations relating to Chinese prisoners, the two major organ transplant hospitals in Queensland, Australia, stopped transplant training for Chinese surgeons and banned joint research programs into organ transplantation with China.In July 2006 and April 2007, Chinese officials denied organ harvesting allegations, insisting that China abides by World Health Organization principles that prohibit the sale of human organs without written consent from donors.In May 2008 two United Nations Special Rapporteurs reiterated their previous request for the Chinese authorities to adequately respond to the allegations, and to explain the source of organs which would account for the sudden increase in organ transplants in China since 2000.