British scientists prospecting the world’s deep-sea basins for oil have discovered that the same technique can be applied to catch drug cheats in sport.

The innovative steroid test developed by researchers at Imperial College, London, and the University of Nottingham uses a process known as hydropyrolysis to detect levels of drugs in urine accurately.

The new test enables anti-doping officials to tell the difference between naturally occurring human steroids and those injected into athletes and racehorses to boost performance.

Steroids produced naturally in the body have a heavier carbon content than synthetic substances but, until now, it has been difficult to measure the different carbon ratios.

Hydropyrolysis, which is most commonly used to aid oil exploration by freeing small fragments of organic matter from petroleum rock sources, is a step forward because it allows forensic scientists to separate carbon molecules without corrupting the original sample.

The inaccuracy of the current steroid test, caused by less sophisticated extraction methods, offers a grey area for drug cheats to hide.

Athletes caught by a positive test can, and do, argue that the test was flawed or that the steroids were naturally occurring as a result of something they ate or drank.

The new test leaves no room for conjecture, according to Mark Sephton, a meteorite specialist at Imperial, who chanced upon the discovery after a casual conversation two years ago with Nottingham’s Colin Snape, a hydropyrolysis expert helping oil firms to assess whether to drill for oil in ocean beds.

“This is unequivocal because the original carbon signature shines through. The carbon-based secrets of steroids are now apparent,” he said.