Three parent babies created with genetic material from three people would be the result of 'genetic engineering' and should not be allowed, a group of scientists will say.

A change in the law to allow doctors to use genetic material from a third person to avoid serious and life threatening diseases is being debated in the UK, The Telegraph reported.

In a letter seen by the Sunday Times to the Commons science and technology committee, which is holding a one-day inquiry into three parent embryos on October 22, a group of scientists said: "The safety of mitochondrial replacement therapy is not yet established sufficiently well to proceed to clinical trials."

The technique in involves replacing faulty mitochondrial DNA in a woman's eggs that would mean she did not pass on diseases such as muscular dystrophy.

Mitochondria are the batteries in human cells it has been argued and that the new DNA would not alter a person's personality or appearance.

However, an editorial in New Scientist said mitochondria "play a key role in some of the most important features of human life. This raises the ethically troubling prospect ... that children conceived in this way will inherit vital traits from three parents."