The Pontifical Academy of Sciences (PAS) said the Chinese former deputy health minister it invited to the two-day summit has been playing a fundamental role in criminalising the practise in China.
Speaking about Dr Huang Jiefu's invitation to the event, which started on Tuesday, Francis Delmonico from PAS told the Guardian: "Dr Huang's understanding of the worldwide objection to that practice was the impetus for his relentless pursuit of the change in China culminating in the ban on the use of organs from the executed prisoner in January 2015."
But Doctors Against Forced Organ Harvesting (DAFOH) claimed there has not been independent inspections to establish whether illegal organ harvesting is still occurring in China. They say China's inclusion compromises the integrity of the conference.
Dr Torsten Trey from DAFOH was quoted by the BBC as saying: "Without accountability, there is no reason to trust the government of China's claim that forced organ harvesting of prisoners has come to an end".
Christians, members of the Falun Gong spiritual movement, ethnic Tibetans and Uighur's are among those who have been imprisoned for the beliefs in China and killed so their organs can be harvested, campaigners claim.
According to China forced organ harvesting ended in 2015, however the International Coalition to End Organ Pillaging in China (EOP) last year claimed the state perpetrated mass killings of innocent prisoners.
Dr Huang Jeifu was quoted by the BBC as saying: "In my governmental organisation there is zero tolerance [to organ trafficking]."
"However, China is a big country, with 1.3 billion people, so sure, definitely, there is some violation of the law.
"If there is some violation of the law it will be severely punished."
The event is calling for organ trafficking to be recognised as a crime against humanity.