Plans to legalise babies being born with three genetic parents in the UK have come a step closer after health officials said they would press ahead with creating new regulations to allow the move.
A consultation was launched about the initiative, which would see the controversial IVF technique used to prevent devastating inherited diseases, earlier this year.
In its response, the Department of Health said that plans to legalise use of these techniques to prevent mothers passing on serious mitochondrial diseases to their children are to progress.
Fertility rules were changed by the Government in February which paved the way for Britain becoming the first country in the world to allow mitochondrial replacement (MR) therapy.
Ministers then launched a consultation on the move and have now issued their response.
A Department of Health spokeswoman said that following some additional work which will take place over the summer regulations will be drawn up to be set before Parliament.
A final decision to allow the treatments will need the approval of both Houses of Parliament but could come as early as next year.
Mitochondria are tiny powerhouses in cells that generate energy and have a small amount of their own DNA, separate from the bulk of the human genetic code.
Defects in mitochondrial DNA (mtDNA) are responsible for a host of inherited diseases, including conditions leading to muscle wasting, heart problems, loss of vision, organ failure and epilepsy.
MR treatment, which employs two different IVF techniques, aims to prevent these diseases by giving babies healthy mtDNA from donor eggs.
The baby is born with normal "nuclear" DNA passed down by its parents - containing most inherited traits such as eye and hair colour and height - plus a tiny amount of mtDNA donated by a second donor "mother".
In effect the baby has three genetic parents, though the donated mtDNA contains less than 1% of its genes.
Since the healthy mtDNA would be inherited by future generations, the treatment has the potential to eradicate mitochondrial diseases from affected families.
Critics argue that allowing the treatments could be the first step down a slippery slope towards "designer babies" and eugenics.
If mitochondrial replacement is permitted, more than 100 "three-parent" babies could be born in the UK each year.
"As the Government's latest consultation has again shown, there is broad public support for making mitochondrial replacement therapy available to patients," said Dr Jeremy Farrar, director of the medical charity the Wellcome Trust.
"There is now no excuse for the Government not to table regulations for debate as soon as Parliament returns this autumn, so that the HFEA (Human Fertilisation and Embryology Authority) can licence clinics to treat affected families without delay once it is satisfied that any risks are acceptable."
Dr Andy Greenfield, chair of the HFEA's expert panel of scientists, said: " Moving from research into clinical practice always involves a degree of uncertainty.
"If Parliament does change the law the regulatory processes required by the HFEA before treatment can be offered will ensure, to the extent that assurance can ever be offered, that mitochondrial replacement works and is sufficiently safe to be offered to people with serious mitochondrial disease."
Sally Cheshire, chair of the HFEA, added: "The decision to change the law is, quite properly, for Parliament and today the Government has signalled its intention to introduce regulations.
"But even if the law is changed that doesn't mean that treatments will be offered overnight. As the regulator, the HFEA will need to design and implement a process to ensure that clinics are licensed against rigorous standards - the public would expect nothing less."