The scientists who cloned Dolly the sheep have formally applied for a licence to clone human embryos to find a cure for motor neurone disease.
Professor Ian Wilmut makes a point during the media briefing
If granted, Professor Ian Wilmut's team at Edinburgh's Roslin Institute would clone cells from MND patients to see how the illness develops in an embryo.
The licensing body, the Human Fertilisation and Embryology Authority, granted a similar licence in August.
The application has provoked criticism from pro-life campaigners.
Therapeutic cloning for research has been legal in the UK since 2001.
In August this year, scientists at the University of Newcastle were given permission to perform therapeutic cloning using human embryos for the first time.
They wanted to duplicate early stage embryos and extract stem cells from them which can be used for radical new treatments for a host of diseases such as
Alzheimer's, Parkinson's and diabetes.
In comparison, Professor Wilmut wants to create cloned embryos with MND.
Professor Wilmut has stressed that his team has no intention of producing cloned babies, and said the diseased embryos would be destroyed after experimentation.
Professor Wilmut said: "I would emphasise that, at this time, our objective is to understand the disease. Knowledge often does have two edges to it.
"We owe it to the people who suffer from [MND] and are going to suffer from it in the future to try to develop treatments for them."
Human embryos would be cloned
MND is caused by the death of cells - called motor neurones - that control movement in the brain and spinal cord.
It affects about 5,000 people in the UK. Half of people with MND die within 14 months of diagnosis.
Weakness in the muscles that supply the face and throat also cause problems with speech and difficulty chewing and swallowing.
The aim is to study what goes wrong in the nerve cells of patients suffering from MND so they can improve their understanding of how the disease develops.
The researchers say cloning is necessary for this because the key cells are in the central nervous system of the sufferers and therefore cannot be analysed themselves.
Professor Wilmut's team plan to take DNA from the skin or blood of a person with MND and implant it into a human egg from which the genetic material has been removed.
The egg would then be stimulated to develop into an embryo.
The scientists would remove cells from the embryo while it was still in the earliest stages of development, and study them to gain a better understanding of the disease.
The embryo would be allowed to develop for around six days, until it was at the blastocyst stage, before being destroyed.
If successful, Professor Wilmut said the technique could have profound implications for a range of other debilitating neurological and genetic disorders.
If the HFEA gives the go-ahead for the research, the Roslin team hope to begin work by around Easter next year.
Brian Dickie, director of research for the MND Association, said: "We will support this research project, as long as we are satisfied that it is legal, has a sound scientific rationale and has the potential to bring us closer to treatments and/or a cure for MND."
However, the charity Life was opposed to the research.
A spokeswoman said: "Human beings should not be manufactured in order to benefit others and that's what research on human embryos consists of.
"For human embryos to be dissected and researched upon for any reason is wrong.
"We hope scientists will be able to discover treatments for all kind of conditions including motor neurone disease, but not through the deliberate manufacture and destruction of human embryos."
Dr Donald Bruce, director of the Society Religion and Technology Project of the Church of Scotland, said: "The aim of the Roslin proposal is laudable, to produce cells which exhibit motor neurone disease for studying the disease and perhaps developing future treatments, but it raises big ethical issues."
Professor Robin Lovell-Badge, from the National Institute for Medical Research, said: "This approach should allow us to study genetic disease without having to use humans as guinea pigs, or indeed, guinea pigs as humans."
Professor Alison Murdoch, Chair of British Fertility Society and Head of Newcastle Centre for Life, who had a successful therapeutic cloning licence application earlier this year, said: "I support this therapeutic cloning application and hope they will be successful."
John Gillot, spokesperson for the Genetic Interest Group, said: "This is clearly early stage research and a treatment is clearly not just around the corner. However, it is no less important for that."