Sparks flew in the afternoon session of the meeting as China's former vice health minister, Dr. Huang Jiefu, sought to assure the international medical community that China was "mending its ways" after declaring an end to the prisoner harvesting programme in 2015.
"I am fully aware of the speculation about my participation in the summit," Huang told the conference, citing "continuing concerns about the transplant activities."
Huang first publicly acknowledged the inmate harvesting organ program in 2005 and later said as many as 90 percent of Chinese transplant surgeries using organs from dead people came from executed prisoners.
He has spearheaded a reform effort and pledged that China put an end to the program in 2015. But doubts persist that China is meeting its pledge, given its lack of transparency, the severe shortage of organ donors and China's longstanding black-market organ trade.
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As a result, China proposed at the Vatican meeting that the World Health Organisation form a global task force to help crack down on illicit organ trafficking.
Dr. Jacob Lavee, president of Israel's transplant society, insisted in response that WHO be allowed to conduct surprise inspections and interview donor relatives in China.
"As long as there is no accountability for what took place ... There can be no guarantee for ethical reform," he told the conference in a heated exchange.
Wang countered that he and Huang spent the past 12 years battling critics inside China and out to reform the sector, and said China shouldn't be singled out for spot WHO inspections.