Ujah, 27, was part of the British team who were pipped to gold by Italy, alongside Zharnel Hughes, Richard Kilty and Nethaneel Mitchell-Blake. Their silver medals are now at risk and, if the ban is upheld, Canada could be upgraded to silver with China receiving bronze.
Ujah tested positive during the Games for two banned substances known as Sarms (Selective Androgen Receptor Modulators): S23, which aids muscle building, and Ostarine, an anabolic agent.
The UK Anti-Doping Agency (Ukad) website describes Ostarine as having “a similar effect to testosterone”. It adds: “Dietary supplements containing Ostarine typically claim to promote muscle building. Unscrupulous manufacturers may market such products as ‘legal steroids’ or ‘steroid alternatives’.”
Ujah has been handed a provisional suspension pending an investigation by the Athletics Integrity Unit.
The AIU announced that three other athletes were also found to have breached anti-doping rules: Bahrain’s middle-distance runner Sadik Mikhou, Georgian shot-putter Benik Abramyan, and Kenyan sprinter Mark Otieno Odhiambo.
The AIU revealed that it had worked with the International Testing Agency to target two of the four athletes, but it did not reveal which two athletes were targeted or why. Kenya and Bahrain are both listed as category A high-risk countries in relation to their doping threat in athletics.