NEW YORK (Reuters) - A New York fertility specialist, who said he successfully carried out a "three-parent" in-vitro fertilisation (IVF) technique resulting in a baby boy, called the procedure a "revolutionary approach in human reproduction".

Dr John Zhang, medical director of New Hope Fertility Centre in New York, spearheaded the technique roughly five months ago with a Jordanian couple at a clinic in Mexico.

The procedure, which the United States government has forbidden due to perceived risks to the mother and child, is designed to help families with mitochondrial diseases passed down maternally, affecting around one in 6,500 children worldwide.

The treatment uses the genetic (DNA) material from the parents and an egg donor to create an embryo. Some stem-cell scientists say Mexico lacks the regulatory oversight and clinical expertise to carry it out safely.

"This new technology, the first time in human history, a healthy live person that is created by two eggs recombined it together with one sperm," Dr Zhang told Reuters during a fertility conference in New York. "This not even has happened in nature."

Dr Zhang said the mother of the baby carries the gene for Leigh syndrome, a fatal and inherited disorder caused by mutations in mitochrondial DNA that affect the central nervous system. Symptoms begin within a year of a child's birth and lead to death within a span of several years.

Dr Egli said that he expects the number of patients seeking such treatments to grow and hopes it will be approved in the US.

"I think it is unfortunate that the political situation here results in the paralysis that does not allow the use of the expertise present here," said Dr Egli. "The outcome for patients would be much better... the way it is now is they cannot keep up with the scientific progress."

Dr Zhang, who is scheduled to present his findings at a meeting of the American Society of Reproductive Medicine on Wednesday in Salt Lake City, Utah, said the questions were all a part of the scientific progress he thinks is being made.

"Eighty per cent of the time there is criticism, and 20 per cent of the time maybe in favour. I think what happened is very healthy and very encouraging," he said.

Dr Zhang said he relished seeing families who have suffered from the death of a child finally able to have a healthy child. "I just feel that I am bringing a gift. I really think it's just a wonderful thing."