Scientists are all set to begin human trials of anti-ageing drugs that could extend a person's life to 120 years.

The Food and Drug Administration in the US has approved the trials of the diabetes drug metformin on humans starting as early as next year. Researchers have already tested the drug on animals which show it significantly extends their lives.

"If you target an ageing process and you slow down ageing then you slow down all the diseases and pathology of ageing as well," said Professor Gordon Lithgow of the Buck Institute for Research on Ageing in California, who will lead the study, reported Daily Mail.

"That's revolutionary. That's never happened before. I have been doing research into ageing for 25 years and the idea that we would be talking about clinical trial in humans for an anti-ageing drug would have been thought inconceivable. But there is every reason to believe it's possible," Lithgow added, according to the Telegraph.

"The future is taking the biology that we've developed and applying it to humans."

Scientists are hopeful that the anti-ageing drugs will also be able to slow down the onslaught of age-related diseases, like Alzheimer's and Parkinson's.

According to the researchers, if the anti-ageing drugs test turns out to be successful, it will essentially mean that a 70 year old would have the mental, physical as well as biological age of a 50-year-old.

Last year, Cardiff University researchers found that patients who were given metformin for diabetes lived longer and stayed healthy as compared to others; even though they should have died eight years earlier on average.

The clinical trial named Targeting Aging with Metformin, or TAME, will begin in the US next year. For the purpose of the trial, scientists from different institutions are collecting funds and recruiting 3,000 participants aged between 70 and 80 who have, or are at risk of, cancer, heart disease and dementia.