The controversial cult which claims to have cloned five babies says it has discovered a way of reversing the ageing process.
The Raelian sect believes it can use stem cells to turn back the clock on any part of the body.
It says it has already carried out experiments which involve shortening ageing human DNA, which stretches over time.
The sect's claims are sure to reignite the controversy surrounding human cloning and the use of stem cells, which are obtained from foetuses.
Experts have admitted the techniques used are "good science" and that reversing ageing is "theoretically possible". However, they criticise the Raelians for refusing to reveal their methods and proof of their claims.
Cult chief Dr Brigitte Boisselier, 47, is set to reveal the details of the work at a conference in London next week. However, organisers, who say the cult used a false name to book their facilities, have now cancelled it.
"As far as I am concerned, this is just not science until they prove it," said Professor Christopher Higgins, director of the Medical Research Council's Clinical Sciences Centre at Hammersmith Hospital.
In an exclusive interview with the Evening Standard, Dr Boisselier said the cult had set up a new company, Stemaid, which is using stem cells. At least two patients are being treated; one has a brain tumour and the other is paralysed after a spinal cord injury.
"We have found a way to cure so many diseases and a way to look like you are 17 years old," she said. "There will be six to nine months demonstrating and then we will be showing everything."
She says she is ready to have the treatment herself because "while my mind is mature, I don't like all my wrinkles".
Unlike the cloning project, which is still shrouded in mystery, Dr Boisselier says details of the stem cell research will be made public, starting with a major press conference in Switzerland next month.
Experts are divided over the claims. Several refused to speak to the Evening Standard, claiming the cult was "absurd".
However, Anne Bishop, a stem cell expert at Imperial College, London, believes there may be some basis to the science.
She said: "What they are talking about doing is theoretically possible, although it has nothing to do with DNA. There are several research groups around the world looking at this. It does, in effect, allow you to turn back the effects of ageing on any cell."
Dr Boisselier says the real significance of her work is the promise of eternal youth. Speaking in Montreal where the cult is based, she said: "A generation is coming that will never die. People can expect to stretch their lives for 50 or 70 years."
She says details will be made public at a medical conference in Switzerland next month. Even if successful, the procedure is highly controversial because the stem cells used are taken from cloned embryos created from the patients themselves.
Clonaid's past claims have been treated with scepticism, not least because of its links with the Raelians, founded by a former French racing driver who claims he is in contact with aliens who created humanity from clones of themselves. Clonaid claimed last year that a cloned baby girl named Eve had been born on 26 December. Dr Boisselier promised that full scientific proof would be offered, but later claimed the parents backed away through fear of exposure in the media.
Today she revealed the existence of a "second generation" of clones whose mothers are now in the final stages of pregnancy.