LONDON -- Parents of a boy who has a rare and potentially fatal blood disease Friday became the first couple in Britain to be granted permission to use in-vitro fertilization to create a sibling whose cells could eventually cure their son, AFP reported..

The couple hope the procedure will later provide their three-year-old son Zain, who suffers from thalassemia, with a viable match for a bone marrow transplant.

In a landmark decision, Britain's In-Vitro Fertilization (IVF) regulatory body ruled that the boy's parents can have a cell removed from a specially selected embryo and checked that it is disease-free and a good tissue match.

If it is suitable, the embryo will be implanted into the womb of Zain's mother, Shahana Hashmi, from Leeds, northern England.

When the baby is eventually born, doctors will take stem cells, which can regenerate bone marrow, from its umbilical cord and inject them into Zain.

Using this technique, doctors said the boy would have an 80 percent chance of a match being found, compared to a 20 percent chance from a sibling conceived naturally.

Although the technique of Pre-implantation Genetic Diagnosis (PGD) is not illegal in Britain, permission must first be sought from the human Fertilization and Embryology Authority (HFEA).

Shahana and Raj Hashmi, who have four children, none of whom is a suitable donor for Zain, had vowed to take their fight to the European Court of Human Rights if their application was rejected.

Friday's decision was immediately condemned by pro-life campaigners, who warned that "manufacturing" a baby would "devalue the respect for human life".

Peter Garret, director of research at Pro-Life Charity Life, said: "This case raises serious questions as to how far we should allow science to go.

"While the term 'designer baby' is often overused, it is all too appropriate in this case. Children should be accepted and loved unconditionally," he added.

Ruth Deech, chairperson of the HFEA, defended the body's decision, saying it would not "set a precedent" for a number of other cases.

"The authority will only approve the treatment in very rare circumstances and under strict controls," she stressed.

In a statement, the HFEA said its licence committee took the decision "in the light of the knowledge that the Hashmis wish to have another child free from the genetic disease which affects their son Zain.

"They also hope that the new baby's cord blood can be used to attempt to save his life.