Brazilian pole vaulter Thiago Braz, the 2016 Olympic champion, has been provisionally banned by the Athletics Integrity Unit (AIU) for a doping offence.
The AIU, an independent body, announced the decision for the presence or use of prohibited substance ostarine.
Ostarine has similar effects to testosterone and is not approved for human consumption in any country.
The 29-year-old also won bronze in Tokyo 2020.
He will be suspended from any activity in athletics until a final decision at a hearing conducted under the World Athletics Anti-Doping rules or the Integrity Code of Conduct.
Braz has not yet commented on the AIU’s decision.
The upcoming World Athletics Championships take place from 19-27 August.