Britain's fertility regulator says controversial techniques to create embryos from the DNA of three people "do not appear to be unsafe", even though no one has ever received the treatment.
The conclusion is largely based on lab tests and some animal experiments and the regulator wants further experiments before patients are treated.
"Until a healthy baby is born, we cannot say 100 per cent these techniques are safe," said Dr Andy Greenfield, who chaired the expert panel behind the report.
The techniques are meant to stop mothers from passing on potentially fatal genetic diseases to their babies and involve altering an egg or embryo before transferring it into a woman.
Such methods have only been allowed for research in a laboratory. But the British Department of Health hopes legislation will be in place by the end of the year that allows treatment of patients.
If approved, Britain would become the first country in the world to allow embryos to be genetically modified this way.
Critics have said the research is unethical and warn the technology has unknown dangers.