(CNN) Organizers of a global genome conference have called for an independent investigation into a Chinese scientist who claims to have created the world's first genetically edited babies, describing his research as "deeply disturbing."
In a statement wrapping up the Second International Summit on Human Genome Editing in Hong Kong, the event's organizing board said He Jiankui's research was "irresponsible" and called for an assessment to "verify this claim and to ascertain whether the claimed DNA modifications have occurred."
He, an associate professor at the Southern University of Science and Technology in Shenzhen, sent shock waves through the scientific community on Monday when he announced in a video posted online that two ostensibly healthy twin girls had been born this month from embryos altered to make them resistant to HIV.
The board, made of up 14 leading geneticists from around the world, warned that even if He's claims are verified, the procedure failed to conform with international norms.
"Its flaws include an inadequate medical indication, a poorly designed study protocol, a failure to meet ethical standards for protecting the welfare of research subjects, and a lack of transparency in the development, review, and conduct of the clinical procedures," the statement said.
Presenting his findings for the first time at the summit on Wednesday, He publicly defended his work, saying he felt "proud" of his achievement. He also raised the possibility of a third child being born, after announcing that a separate woman was pregnant at an early stage with a modified embryo.
He's research has raised serious ethical questions around the transparency of gene editing and sparked calls from some attending the event for a globally binding code of conduct.
Scientists reiterated an agreement made at the previous conference in 2015, that said it would be irresponsible to use such genetic editing until safety issues had been dealt with.
"While we applaud the rapid advance of somatic gene editing into clinical trials, we continue to believe that proceeding with any clinical use of germline editing remains irresponsible at this time," the statement said.
Germline gene-editing refers to genetic changes in every cell, that will be passed on to future generations. This is different to somatic (body) cell gene-editing, whereby only existing cells are targeted and the changes made are not passed on to future offspring.
Conference Chairman and Nobel laureate David Baltimore acknowledged that verifying He's claims would be challenging as no one knows who or where his subjects are.
"We have called for an investigation but we haven't laid out how to do it, because it depends on what kind of cooperation we get from him," Baltimore said.
Separately, He is the subject of an investigation by the Chinese government.
In a joint statement issued Monday, more than 120 Chinese scientists condemned He's use of the CRISPR-Cas9 gene-editing tool as a "huge blow" to the reputation of Chinese biomedical research.
"It's extremely unfair to Chinese scientists who are diligent, innovative and defending the bottom line of scientific ethics," they wrote, adding that "directly experimenting on humans is nothing but crazy."
Both the hospital named in He's ethical approval documents, and the university he is affiliated with, have denied any involvement in the procedures.
Organizers on Thursday proposed establishing standards for preclinical evidence and accuracy of gene modification that include "enforceable standards of professional behavior."
Currently, each country has their own rules and regulations surrounding gene-editing.
Speaking in a question-and-answer session after He's presentation on Wednesday, Baltimore said the case showed that "there has been a failure of self-regulation by the scientific community because of the lack of transparency."
That He could tinker with life changing technology away from the eyes of regulators has caught many in the scientific community on the back foot.
"We did not know this was coming," Jennifer Doudna, professor of chemistry and molecular and cell biology at UC Berkeley and one of the co-inventors of CRISPR told CNN.
"I hope this is a wake-up call for everybody to recognize that while this technology is incredibly exciting, this is an important moment where we need to grapple with responsibility of managing this technology going forward."
Days before the conference Feng Zhang, also a co-inventor CRISPR, and member of the Broad Institute of MIT and Harvard, called for a moratorium on using the technology to edit the genes of babies.
"The technology is still very early and there are a lot of challenges that need to be resolved," he told CNN. Zhang acknowledged that regulating this type of research would be difficult but said it was important to come up with "a set of requirements for how to put forward a comprehensive and informative application for experimental medicine development."
"We can do more on that front," he said.