A professional footballer has tested positive for the anabolic steroid nandrolone for the first time in England.
The Football Association are investigating the positive test, which occurred within the past three months.
But they are keeping the identity of the player secret until the inquiry has been completed. The FA is refusing even to reveal which division he plays in or whether he is British or not.
The finding of 19-norandrosterone, a metabolite of nandrolone, was revealed in UK Sport's quarterly anti-doping report.
The FA is treading cautiously as positive nandrolone tests have been a source of huge controversy in the past.
The human body is thought to produce minute amounts of the substance naturally, and several leading sports stars in the past have not been punished for positive tests. Some scientific experts believe that some dietary supplements are contaminated with the steroid.
Earlier this year, the FA sent every club and every player warnings about the possible use of contaminated dietary supplements.