The HFEA, which carried out the consultation, advised ministers that if they do legalise the therapy, donors and patients should remain anonymous and have no right to contact one another.
At first patients should only be considered on a case by case basis but in future the treatment could be suitable for wider use in clinics, the watchdog added.
Further tests are needed to ensure the therapy is safe and effective, but researchers are confident it could be available within a few years and up to 10 women at high risk of passing on the diseases to their children could be treated each year.
Prof Lisa Jardine, chair of the HFEA, said: "We have found that there is broad support for permitting mitochondria replacement, to give families at risk of mitochondrial disease the chance of having a healthy child.
She added that Britain is at a more advanced stage of legalising the treatment than any other nation, claiming that other countries are astounded that were this far on in the discussions.
Dismissing fears that allowing the treatment could be the start of a slippery slope, she emphasised that the therapy - which could become the first treatment to alter the human germ line - would only be available for people at risk of passing on mitochondrial disease.
The treatment is designed to eliminate the risk of diseases caused by faulty mitochondria, rod-like structures which supply energy to our cells, by substituting them with those of a healthy donor.
Although 99.8 per cent of our DNA, including the parts which govern all our visible characteristics, are contained in the cell's nucleus, a small fraction including the mitochondria sits elsewhere in the cell.
The technique involves removing the nucleus from an unfertilised egg, or from the bundle of mother's and father's nuclear DNA after fertilisation, and implanting it into the shell of a healthy donor egg.
The egg from the donor would first have its nucleus removed, meaning the baby would inherit their identity solely from their mother and father, but get their energy-supplying mitochondria from the third person.
Originally posted here:
Britain on course for 'three parent babies'