The CoolTouch laser invisibly stimulates the growth of new collagen - a fibrous material that holds the skin together - without marking the surface.

Developers claim the treatment is painless, leaves no blemishes, and can be completed in minutes.

A clinical trial in the US showed significant effects after just two treatment sessions, lasting 15 to 30 minutes.

The laser stimulates cells called fibroblasts to produce new collagen and elastin fibres.

Four months later the skin is plumped out and a large proportion of fine lines and wrinkles have vanished.

The treatment was developed in the United States over the past three years and licensed for use on American patients 18 months ago.

Alternative laser treatment burns off the top layer of skin, and can cause painful reddening for months.

Dr Gregory Chernoff, a facial plastic surgery specialist who conducted the 18-month clinical trial in Santa Rosa, California, and Indianapolis, Indiana, said: "I was a non-believer at first. I didn't think it would have much of an effect.

"It was my patients who changed my mind, because they were coming back months later and telling me how amazed they were.

"Even after six weeks they started seeing a softening in their lines and wrinkles."

Usually two treatments are given about six weeks apart. For best results a "top up" treatment session should be repeated once every six months to a year after that.

A hand-held laser gun shoots pulses of concentrated red light into the dermis, deep under the skin surface, where the fibroblasts are situated.

The cells are heated, briefly, to 80 degrees Celsius which causes them to start manufacturing new collagen.

Just before the laser fires, the gun shoots a jet of freezing spray on the skin which stops it burning and protects the sensitive nerve endings.

In the trial, two-thirds of a group of 212 patients saw positive results after being treated only once. The remaining third saw an improvement after a second or third session.

Analysis of surgically removed sections of skin showed a packing together of collagen in the upper area of the dermis as well as the formation of new collagen.

The findings have been submitted to the Plastic and Reconstructive Journal, a respected avenue for publishing plastic surgery research.

The treatment is particularly effective at removing fine lines from around the eyes and mouth, and also acts as a preventative measure to slow the effects of ageing.

However, it will not banish laughter or frown lines, which are both caused by muscle movement rather than collagen loss.

It works best for people in their 30s and 40s who have not yet lost too many of their fibroblasts, which reduce with age. Men are said to respond especially well.

As well as combating the effects of sun, smoking, stress and neglect, the treatment is also said to help reduce acne scars and stretch marks.

One treatment session at the Harley Medical Group clinic in Harley Street, London, where CoolTouch is being pioneered in the UK, costs £350.

Mel Braham, group chairman of the Harley Medical Group, said: "We think this is a sensational breakthrough. It's amazing to think that a patient can come in during their lunch hour, have this laser treatment, and then return to work without anyone knowing where they have been."

However, Dr Nick Lowe, a consultant dermatologist, warned the treatment could backfire.

He said: "What we don't know is whether it is safe to repetitively reheat that collagen. It is quite possible that if collagen is reheated on many occasions it may actuallly increase the ageing of the skin."