An American scientist has created a cloned embryo from his own skin cells, becoming the first person to create an exact copy of their genetic make-up.

Samuel Wood, a researcher at Stemagen Corporation in La Jolla, California, plucked cells from his skin and injected them into donated eggs that had been treated to remove their own genetic material.

The eggs developed into very early stage embryos that were genetically identical to the scientist's own DNA.

The research is a step towards scientists' goal of creating supplies of embryonic stem cells genetically matched to patients, which could potentially be used to regenerate diseased or damaged tissues without the risk of immune rejection.

It is not the first time human cloned embryos have been created. In 2005, scientists led by Miodrag Stojkovic at Newcastle University used embryonic stem cells to produce a cloned embryo. It survived for only a few days and no stem cells were extracted from it.

The Stemagen team did not retrieve stem cells from their clones either, leading some scientists to question the importance of the work. Eggs were taken from women aged 20 to 24 and used within two hours, according to a report in the journal Stem Cells. Dr Stojkovic, a co-editor of the journal, said: "This is a key advance in the development of patient-specific stem cell lines for therapeutic purposes."

Dr Stephen Minger, a stem cell researcher at King's College London, said: "Disappointingly, the researchers did not go on to do the next step: to create embryonic stem cell lines from cloned embryos. The community is waiting with bated breath to see if anyone can do both steps. Having access to specific stem cell lines would allow us to research major diseases such as Parkinson's and spinal muscular atrophy."