The Church of England has said it would be 'irresponsible' to introduce laws to allow 'three parent babies' in the UK, ahead of a parliamentary vote on the issue next week.
On Tuesday MPs are due to vote on whether to change the Human Fertlisation and Embryology Act 2008 and legalise mitochondial replacement therapy.
According to the Telegraph, the Church of England announced yesterday that it could not support the legislation.
Under the proposed legislation, IVF clinics would be able to replace defective mitochondrial DNA from an egg with healthy DNA given by a donor. This would reduce the number of children born with serious inherited diseases such as muscular dystrophy, but would also mean those children would technically have two mothers, or three parents in all.
The Church has expressed concerns that the vote will happen ahead of peer-reviewed safety checks into the technology.
The Church of England's national adviser on medical ethics, Rev Dr Brendan McCarthy, told the Telegraph: "The Archbishops Council, which monitors this issue, does not feel that there has been sufficient scientific study or informed consultation into the ethics, safety and efficacy of mitochondria transfer.
"Without a clearer picture of the role mitochondria play in the transfer of hereditary characteristics, the Church does not feel it would be responsible to change the law at this time."
A number of leading scientists have called on MPs to support the legislation. In a letter to the Times this week, which was signed by five Nobel laureates, the signatories said parents of children with mitochondrial diseases "should not have to wait for law to catch up" with science.
"We believe that those who know what it is like to care for, and sometimes to lose, an extremely sick child are the people best placed to decide whether this technology is right for them, with medical advice and within the strict regulatory framework proposed. They have been waiting for the science for long enough. They should not have to wait for the law to catch up," they said.
The signatories include Sir Paul Nurse, president of the Royal Society, Sir John Gurdon, who won the 2012 Nobel Prize in Physiology or Medicine, and the Rt Rev Lord Harries, a former bishop of Oxford.
"The question that parliamentarians must consider is not whether they would want to use this technology themselves, but whether there are good grounds to prevent affected families from doing so."
Christian charity CARE criticised the letter, underscoring the safety concerns about the legislation.
"Not for one minute would we deny that mitochondrial diseases are terrible to deal with. But this letter completely fails to acknowledge the substantial and real safety concerns that exist over the new IVF regulations," a CARE spokesperson said.
If parliament supported the bill, the UK would be the first country to permit the procedure, but scientists would have to apply to the Human Fertilisation and Embryology Authority for a licence.
The letter said that licences would only be granted when safety issues were resolved. "A vote in favour will not allow clinics to offer mitochondrial donation immediately: they will still need a licence... which will be granted only with scientific evidence that any risks in each particular case are low. Passing the regulations now will allow this licensing process to begin, so that families do not face further delay," they said.
When the issue was last debated in Parliament in the autumn, a number of MPs expressed concerns about the ethics of making changes to our DNA.
Conservative MP Fiona Bruce, who is a Christian, said in the September debate: "This is a case of genetic engineering; it is the alteration of a potential human being – the removal of certain genes and their replacement with others, to create children."
CARE also expressed additional concerns: "For every new human embryo created by one of the techniques the Government is proposing, at least two other human embryos are destroyed – that's viable life being destroyed.
"More and more evidence also seems to indicate mitochondrial DNA informs the characteristics of the child and because of this CARE is firmly of the view that the term 'three parent children' is entirely accurate.
"The reality is we don't know all there is to know about how this technique will affect the child and there is a strong possibility any child created using this new technique would have to be monitored for the rest of their life."
The charity added that it was "quite extraordinary" that the government is asking MPs to vote on this controversial legislation so close to an election.