A human embryo has been cloned for the first time in Britain, where such work is strictly regulated, scientists announced.
Scientists at Newcastle University, the first in Britain to obtain a licence to carry out therapeutic cloning for stem cell research, said they had successfully produced a blastocyst -- a tiny, early-stage embryo consisting of a hollow ball of cells -- cloned from a human cell using nuclear transfer.
Scientists hope the work will eventually lead to successful treatments for degenerative diseases such as Parkinson's and Alzheimer's, or for the paralysed victims of spinal injuries.
The announcement came on the same day that a team of South Korean scientists announced they had developed the first lines of patient-specific stem cells, designed to match the DNA of a specific person.
This research marks a significant stride in work aimed at making it possible one day to transplant healthy cells into humans to replace cells ravaged by illnesses such as Parkinson's, said the researchers.
The British scientists said they were "delighted to hear of the great progress" made by the Koreans.
"They have shown conclusively that these techniques can be successful in humans. The promise of new treatments based on stem cell technology is moving nearer to becoming a realistic possibility," two members of the British team, Professor Alison Murdoch and Dr Miodrag Stojkovic said in a joint statement.
"During the past nine months in Newcastle, our research in nuclear transfer has progressed well. Our preliminary data will be published soon.
Reproductive cloning is banned in Britain, and a breach can result in a 10-year prison sentence.