A law change would allow for children to be 'designed' to be free of horrific diseases.
The children would effectively have two mothers and one father and the technique could lead to the creation of designer babies, made to order by hair or eye colour.
Germline therapy, or the alteration of genes in eggs or sperm, is banned in most countries, the 'Daily Mail' reported.
"We find ourselves in uncharted territory, balancing the desire to help families have healthy children with the possible impact on the children themselves and wider society." Lisa Jardine, of the Human Fertilisation and Embryology Authority, a government watchdog, said.
Serious defects affect around one in 6,500 babies and cause around 50 genetic diseases, many of which kill in infancy.
These conditions are caused by defects in the DNA of mitochondria
