The Chinese government has ordered an "immediate investigation" into the alleged delivery of the world's first genetically edited babies, as experts worldwide voiced outrage at such use of the technology.

The pushback comes amid claims made online by Chinese scientist He Jiankui that twin girls had been born with DNA altered to make them resistant to HIV, a groundbreaking move that is likely to spark significant ethical questions around gene editing and so-called designer babies.

He, a professor at Southern University of Science and Technology in Shenzhen, claims that his lab had been editing embryos' genetic codes for seven couples undergoing in-vitro fertilization.

In a video posted to YouTube on Monday, the Chinese researcher said that one of the pregnancies had been successful and that ostensibly healthy twin girls Lulu and Nana had been born "a few weeks ago."

He claims that he used a tool known as CRISPR-cas9, which can insert or deactivate certain genes. In his YouTube video, He describes the procedure as having "removed the doorway through which HIV enters."

He's claims have neither been independently verified nor peer-reviewed. Editing the genes of embryos intended for pregnancy is banned in many counties, including the United States. In the UK, editing of embryos may be permitted for research purposes with strict regulatory approval. It is unknown whether the procedure is safe or, if used in pregnancy, whether it can have unintended consequences for the babies later in life or for future generations.

China has invested heavily in gene-editing technology, with the government bankrolling research into a number of world "firsts," including the first use of the gene-editing tool CRISPR-Cas9 in humans in 2016 and the first reported use of gene editing technology to modify nonviable human embryos in 2015.

More recently researchers in China claimed to have bred healthy mice from same-sex parents, using gene editing technology.

But in a statement posted Tuesday morning, China's National Health Commission said that it had "immediately requested the Guangdong Provincial Health Commission to seriously investigate and verify" the claims made by He Jiankui.

The statement follows moves by the Chinese hospital named in He's ethical approval documents, Shenzhen Harmonicare Women's and Children's Hospital, to distance itself from involvement in the procedures.

"We can ensure that the research wasn't conducted in our hospital nor were the babies born here," a hospital representative told CNN. The hospital confirmed that two of the doctors named in He's documents work at the hospital and suggested that an internal investigation was underway.

The Shenzhen Health and Family Planning Commission denounced the legitimacy of the hospital ethics committee and the review process that approved the application. It confirmed that an investigation was launched Monday to "verify the authenticity of the ethical review of the research reported by media." (CNN)

• Qin Jinzhou, an embryologist who works at He Jiankui's lab in Shenzhen, gazes through a microscope. Image: AP

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