British sprinter CJ Ujah's 'B' sample has tested positive, confirming the result of his initial test from the Tokyo Olympics.
Ujah, 27, was part of the British men's 4x100m relay team which won silver at the rearranged 2020 Olympics.
They will now almost certainly lose those medals as a result of the tests.
He was provisionally suspended when a test taken at the Games - his 'A' sample - tested positive for banned substances Ostarine and S-23.
Ostarine is listed as an anabolic agent - banned at all times - in the World Anti-Doping Agency's (Wada) list of prohibited substances.
The UK Anti-Doping (Ukad) website said it has "similar effects to testosterone".
S23 is a Selective Androgen Receptor Modulator (Sarm), which, according to the United States Anti-Doping Agency (Usada) has "similar anabolic properties to anabolic steroids".
The case has now been referred to the Court of Arbitration for Sport Anti-Doping Division (CAS ADD).
