The breakthrough at Newcastle University comes as MPs get ready to debate the future of such research.

Embryos were created by implanting DNA derived from human skin cells into eggs taken from cows ovaries with virtually all their genetic material removed.

These lasted for up to three days in the laboratory.

The work is part of investigations into a number of illnesses and the university has said they may ultimately lead to the development of new therapies for debilitating human conditions such as Parkinson's Disease and strokes.

Professor John Burn, Head of the Institute of Human Genetics at Newcastle University, said the research was licensed by the UK's fertility regulator, the Human Fertilisation and Embryology Authority (HFA).

He said scientists used animal eggs because those from humans were in short supply.

"Human eggs are very precious and the idea came forward that you could get around the shortage by using cows eggs instead," he said.

"Now, it is illegal and unsafe to put these cells into a human being, but they are very useful for research purposes."

By law hybrid embryos have to be destroyed after 14 days.