The Human Fertilization and Embryology Authority said in a report published June 3 that it had seen no evidence to suggest that two mitochondrial replacement techniques were dangerous.

British politicians earlier complained to Jeremy Hunt, secretary of state for health, that the creation of so-called "genetically modified" children from the genetic material of three or more parents may carry unforeseen consequences that will harm generations to come. However, Peter Braude, a member of the HFEA review panel, said in a statement that the technologies offered "great hope" to children with inherited mitochondrial disorders. He said that three years of research by the panel would possibly result in "a shining example of evidenced-based regulation."

The report by the regulator comes four months after the British government published draft regulations for the use of maternal spindle transfer and pronuclear transfer procedures to prevent mothers from passing on serious mitochondrial diseases to their children. Neither of the techniques has been carried out on humans around the world and they remain illegal in the U.K., but research has been conducted on animals. The technologies also are prohibited by the European Union, are opposed by the United Nations, and have been under review by the U.S. Food and Drug Administration, which stated earlier this year that the "full spectrum of risks ... has yet to be identified."

The HFEA report allows the British government to move forward on creating a legal framework on the techniques later this year.

Pro-life parliamentarians criticized the HFEA report.

"Given the safety concerns which have been raised, the unresolved ethical questions, and a practice which runs contrary to international consensus, it would be prudent for the U.K. to wait at least until these issues have been resolved before being stampeded into a decision which has such far reaching consequences," Lord Alton of Liverpool, a Catholic member of Parliament, said in a statement.

"This ranks alongside our earlier unwise decision to fly in the face of the concerns expressed about the creation of animal-human hybrid embryos, subsequently shown to be without scientific merit and ethically flawed," he added.

Fiona Bruce, a Conservative Party Member of Parliament, said in a statement that Britain risked "isolating itself from the rest of the world."

"Many MPs are gravely worried about the safety of these proposals, the fact that they have not been properly tested and the very real risk that they could open the door to designer babies," she said.

The government argues the technologies, which utilize in vitro fertilization, are necessary to create between five and 10 healthy babies a year for couples who might pass on mitochondrial diseases.

Mitochondria are the biological power packs that give energy to nearly every cell of the body. Genetic defects can leave the cells starved of energy, causing muscle weakness, blindness, heart failure and death in the most extreme cases. It is estimated that defective mitochondria affect one in every 6,500 babies in the U.K. annually.

The maternal spindle transfer technique involves the extraction of the genetic material from a mother's egg, which is then inserted into a donor egg in which the maternal spindle has been removed and discarded. The reconstituted egg then is fertilized by the father's sperm before implantation in the mother. The procedure is known as "three-parent IVF."

The second technique, pronuclear transfer, involves up to four parents. Potential parents would go through the procedure for in vitro fertilization with the embryo from the parents seeking a child to be combined with parts of a donor embryo. The process requires that both embryos be destroyed while the mother's embryo is effectively cloned and repackaged before the cells begin to multiply and grow into a baby.