Britain's fertility regulator has approved controversial techniques allowing doctors to create babies using the DNA from three people — what it called a "historic" decision that is expected to help prevent a small number of children from inheriting potentially fatal diseases from their mothers.

British MPs had voted in February to allow the creation of in-vitro fertilisation (IVF) babies with DNA from three people, but clinics needed the approval of the Human Fertilisation and Embryology Authority before introducing the treatment.

The technique would allow women who carry disease-causing mutations in their mitochondrial genes to give birth to genetically-related children free of mitochondrial disease.

The regulator's chair, Sally Chesire, on Thursday described it as a "life-changing" moment for families who might benefit from the treatment. She said the techniques would be used in "limited circumstances" as recommended by their expert panel.

Britain's fertility regulator said clinics must apply for permission to use the techniques for every interested patient.

An independent panel of experts last month said the practice should be "cautiously adopted" to prevent certain genetic diseases from being passed on to future generations.

Mitochondria are structures in cells which generate vital energy and contain their own set of genes called mDNA which is passed through the mother.

Mitochondrial diseases cause symptoms ranging from poor vision to diabetes and muscle wasting and health officials estimate around 125 babies are born with the mutations in Britain every year.