British sprinter CJ Ujah said he was "shocked and devastated" after a positive drugs test that could see his country stripped of their Olympic silver medal in the 4x100m relay.
The 27-year-old ran the first leg of the final in Tokyo as Britain narrowly missed gold, but has been provisionally suspended after prohibited substances showed up in tests.
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"To be absolutely clear, I am not a cheat," Ujah said in a statement to the PA news agency on Saturday.
"I have never and would never knowingly take a banned substance."
On Thursday Ujah was informed of an Adverse Analytical Finding (AAF) from a test carried out during the Olympics, showing the presence/use of muscle-building ostarine and S-23.
Ujah's relay team mates were Zharnel Hughes, Richard Kilty and Nethaneel Mitchell-Blake, whose medals will also be at risk if the positive is confirmed.
{{/usCountry}}Ujah's relay team mates were Zharnel Hughes, Richard Kilty and Nethaneel Mitchell-Blake, whose medals will also be at risk if the positive is confirmed.
{{/usCountry}}In his statement, Ujah said: "I am completely shocked and devastated by this news. I love my sport and I know my responsibilities both as an athlete and as a team mate.
"I am respecting the formal processes and will not be making any further comment until it is appropriate to do so."