Scientists have finally made the long-awaited breakthrough in human cloning by turning skin cells into early-stage embryos that were then used to create specialized tissue cells for transplant operations, Belfast Telegraph said.

For the first time, researchers have unequivocally created human embryonic stem cells using the cloning technique that led to the birth of Dolly the sheep. However, unlike Dolly, the human embryos were destroyed when their stem cells were extracted.

The scientific milestone, which comes 17 years after the birth of Dolly, represents a major turning point in human cloning research that could now lead to new tissue-transplant operations for a range of debilitating disorders, such as Parkinson's disease, multiple sclerosis, heart disease and spinal cord injuries.

However, the breakthrough will also raise serious ethical concerns about the creation of human embryos for medical purposes and the possible use of the same technique to produce IVF embryos for couples wanting cloned babies -- which is currently illegal in the UK. The scientists who made the advance emphasised that the work was designed to produce replacement tissue for transplant operations from a patient's own skin cells, rather than to improve the chances of so-called "reproductive cloning".

However, other scientists said the achievement inevitably brought the prospect of cloned babies a step nearer.

Generating a plentiful supply of embryonic stem cells from a patient's own skin cells has been one of the holy grails of medical science.

Although the procedure has been achieved in laboratory animals -- such as mice and monkeys -- it has until now alluded several attempts on human material.

Shoukhrat Mitalipov, who led the research team at the Oregon Health and Science University in Portland, said that he added caffeine to his cell cultures to create viable embryonic stem cells from just a small number of human eggs.