The 29-year-old won world gold in the under-75 kilograms kumite category in Madrid in 2018, and had qualified for Tokyo through the World Karate Federation's (WKF) Olympic rankings.

However, the WKF said Asgari had been banned for use of a "prohibited substance" and would be suspended from international competition for 12 months. 

It has been reported by mtvuutiset that the substance involved is clomiphene, and that Asgari failed a test at the Karate 1-Premier League event in Lisbon in May.

insidethegames has asked the WKF for confirmation.

Asgari has also won three World Championship gold medals in team events.

He won the Asian Games title in Jakarta-Palembang in 2018.

American Thomas Scott will now compete at under-75kg in Tokyo after taking the Iranian's spot.

Nicknamed "Captain America", he benefits as the highest ranked athlete in the Olympic standings who had not qualified for the Games.

The 31-year-old has won gold at the last two editions of the Pan American Games, in Toronto in 2015 and Lima in 2019.

Currently ranked sixth in the world, he is also a five-time continental champion.

Scott becomes the fourth member of the American team for karate's Olympic debut - joining Ariel Torres, Sakura Kokumai and Brian Irr.

Karate at Tokyo 2020 is set to take place between August 5 and 7 at the Nippon Budokan.

The sport has not retained its place on the Olympic programme for Paris 2024, meaning many athletes will likely have just one chance on sport's grandest stage.