"Allegedly the exhibits are sourced from the unclaimed corpses of people who have died in hospital," the letter reads. "However, it is not possible the bodies were 'unclaimed', as according to [Chinese] regulations and autopsy rules ... bodies can only be declared 'unclaimed' after 30 days. "The plastination process, which involves the use of silicon, epoxy, and other polymer mixtures to replace the fluid in the human body, must occur within 48 hours of death. Therefore, it is not possible to plastinate a corpse that is 30 days old." The exhibition has labelled the accusations "offensive" and says it is a wonderful educational experience. However the chief executive of Imagine Exhibitions, the company behind the Real Bodies show, has rejected the allegations.

Speaking to Fairfax Media, Tom Zaller said the claims contained in the letter are "ridiculous" and have "no basis". "I've been doing these exhibitions in one form or another since 2003," he said. "We have been down this road so many times. "There's absolutely no truth in what's being said. The bottom line is all of the specimens used in our exhibition are legally sourced and they have all died from natural causes, which has been expressed since the beginning of these exhibitions touring – as well as forensic anthropologists." Zaller said the exhibition is educational and there was no "foul play" whatsoever. "Everything is done through the right processes," he said.

The chief executive said it was untrue that the plastination process needs to start 48 hours after a person has died. "Plastination, in layman's terms, is the removal of any liquids," he said. "It doesn't matter how old it [the specimen] is; that's the process. It could be 100 years old." The specimens for the Real Bodies exhibition were sourced from Dr Hong-Jin Sui, an anatomy expert from China's Dalian Medical University. In 2008, the organisers of an unrelated anatomy exhibition – but one that Zaller worked on – were forced to add a disclaimer to their website saying they were unable to independently verify their exhibits were not the bodies of executed Chinese prisoners. The statement came after a US congressional inquiry, as well as an investigation by New York's then attorney-general. An exhibit from the Real Bodies exhibition, now showing in Sydney. Credit:Supply

The inquiries were sparked by a story on the ABC's 20/20 program. The American public broadcaster later reported that a source lied to its journalists because Dr Sui was a competitor. France and Israel have banned similar exhibitions featuring preserved bodies. The group of concerned Australian lawyers and academics argue local lawmakers should follow suit. "We are astonished that visas and permits for bringing this exhibition into Australia were issued by the Australian government given the lack of documentation demonstrating ethical and legal sourcing of each body," the group wrote. "No motivation for profit or political sensitivities could ever justify such a crass and undignified violation of human rights." Various human rights organisations have raised concerns about an alleged black market for cadavers in China over the years. Others have said that even if the specimens come from uncollected bodies, they should only be displayed if it can be absolutely verified that the person wanted their corpse donated to science.

Details of a human body as seen at the Real Bodies exhibition at Kennedy Hall. Credit:AAP But not everyone believes such exhibits are offensive. The Real Bodies exhibits have been inspected by the NSW health department and are suitable for people aged four years and over, according to organisers. In a statement promoting the exhibition, Gavin Burland from the Sydney School of Veterinary Science said the show is a great educational experience. "These plastinates provide a unique view into the human body that is normally reserved to the medical field," he said. "The public will be able to explore and interact with these displays to better understand what's inside that makes us function as people." The Real Bodies exhibition is currently showing at Sydney's Byron Kennedy Hall from 10am to 5pm, with tickets selling from around $30.

More than 200 human specimens are on display.