However a team at the Research Institute for Stem Cell Research at CHA Health Systems in Los Angeles and the University of Seoul said they had achieved the same result with two men, one aged 35 and one 75.

"The proportion of diseases you can treat with lab-made tissue increases with age. So if you cant do this with adult cells it is of limited value, said Robert Lanza, co-author of the research which published in the journal Cell Stem Cell

The technique works by removing the nucleus from an unfertilised egg and replacing it with the nucleus of a skin cell. An electric shock causes the cells to begin dividing until they form a blastocyst a small ball of a few hundred cells.

In IVF it is a blastocyst which is implanted into the womb, but with this technique the cells would be harvested to be used to create other organs or tissues.

However, the breakthrough is likely to reignite the debate about the ethics of creating human embryos for medical purposes and the possible use of the same technique to produce cloned babies which is illegal in Britain.

Although the embryos created may not give rise to a human clone even if implanted in a womb, the prospect is now scientifically closer.

However scientists have been trying for years to clone monkeys and have yet to succeed.

Dr Lanza admitted that without strong regulations, the early embryos produced in therapeutic cloning could also be used for human reproductive cloning, although this would be unsafe and grossly unethical.

However, he said it was important for the future of regenerative medicine that research into therapeutic cloning should continue.

Reproductive biologist Shoukhrat Mitalipov of Oregon Health and Science University, who developed the technique last year said: "The advance here is showing that (nuclear transfer) looks like it will work with people of all ages.

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Breakthrough in human cloning offers new transplant hope