A Chinese researcher’s claims on Monday that he had created the world’s first genetically edited babies have reignited concerns that China’s race to lead biomedical research involves disregarding ethical boundaries long accepted elsewhere.

On Monday, Chinese researcher He Jiankui said he had successfully altered the DNA of twin baby girls to make them more resistant to HIV.

Mr He’s claims have not been independently verified, but if true the development would be significant.

Some experts argue that gene editing could change the world for the better by eradicating inheritable illnesses and eliminating microbes that cause diseases.

But it also would allow scientists to create genetically engineered “designer babies” by changing traits such as eye colour or, most controversially, intelligence.

The ethics of tampering with DNA – the source code of life – has been hotly debated and restricted in Western countries including the UK, US, Canada, and Australia.

Scientists in China, however, are largely free to experiment with the technology, despite it being so new that experts simply don’t yet know the long-term impact.