British Olympic sprinter Chijindu Ujah has been provisionally suspended under an anti‑doping rule violation after returning positive results relating to two banned substances.
The violation was confirmed by the Athletics Integrity Unit, which revealed a presence of prohibited substances Ostarine and S-23, which are selective androgen receptor modulators known to mimic testosterone.
Should Ujah's ban be upheld, it would see the entire Great Britain 4x100 Men's relay team stripped of their silver medals, tainting the team's 65-medal haul in Tokyo and marking arguably the largest Olympic doping scandal in British Olympic history.
The International Testing Agency later confirmed it'd collected the in-competition test following the 4x100m relay final.
"The result was reported by the WADA-accredited laboratory of Tokyo on 8 August 2021," the ITA said in a statement. "The athlete has the right to request the analysis of the B-sample.
"If requested by the athlete and if the B-sample analysis confirms the adverse analytical finding … the case will be referred to the anti-doping division of the court of arbitration for sport for adjudication.
"It will consider the matter of the finding of an anti-doping rule violation and the disqualification of the men's 4x100 relay results of the British team."
The Athletics Integrity Unit also confirmed Bahrain's1,500m runner Sadik Mikhou, Georgian shot-putter Benik Abramyan and Kenyan sprinter Mark Otieno Odhiambo had also been suspended.