The scientist who led the team that controversially created Dolly the sheep is abandoning the cloning of human embryos in stem cell research.
An egg being collected for stem cells used for cloning
Professor Ian Wilmut, of Edinburgh University, believes a rival method developed in Japan holds the key to curing serious medical conditions.
The new method creates stem cells from fragments of skin and could remove the need to use human embryos.
Pro-life groups opposed to the use of embryonic cells have welcomed the move.
But Prof Wilmut said: "We've not made this decision because it's ethically better.
"To me it's always been ethically acceptable to think that if you could use cells from a human embryo to develop a treatment for a disease like motor neurone disease, for which there is no treatment at present, then that is an acceptable thing to do."
The professor's team developed a cloning technique that has subsequently been used to harvest stem cells - which have the potential to be grown into any cell in the human body.
Embryonic stem cells are widely regarded as the most flexible cells in the body and could one day be used to produce transplant tissues to treat degenerative diseases.
But the Ian Wilmut has now embraced a technique developed by Professor Shinya Yamanaka of Kyoto University, Japan, that involves genetically modifying adult cells to make them almost as flexible as stem cells. The research has been conducted on mice.
Professor Wilmut said his own research team held a meeting at which it was agreed the Japanese method had more potential than the use of embryonic cells.
He said: "The work which was described from Japan of using a technique to change cells from a patient directly into stem cells without making an embryo has got so much more potential.
"Even though it's only been described for the mouse, when we were considering which option to pursue, whether to clone or whether to copy the work in Japan, we decided to copy the work in Japan."
The eventual aim is to grow replacement tissue as body parts become worn out.
Dolly the sheep was unveiled to the world in 1997
There is some way to go before Professor Yamanaka's method can be used to grow tissue for transplantation as the resulting cells are unstable and potentially cancerous.
But Professor Wilmut believes that within five years the new technique could provide a better and ethically more acceptable alternative to cloning embryos for medical research.
Josephine Quintavalle, spokeswoman for Comment on Reproductive Ethics which is against the use of human embryos, welcomed the move.
She said: "At last scientists are starting to see reason. It is a gift to us all. We are at last going to see some common sense coming into the debate."
In 1997 Professor Wilmut's team made headlines around the world when they unveiled Dolly, the first mammal to be cloned from an adult cell.