British sprinter CJ Ujah's B sample from the Tokyo Olympics has tested positive for banned substances, the International Testing Agency (ITA) has announced.

Ujah provided the sample on 6 August, the ITA said, the same day that he was part of the British team which won silver in the men's 4x100 metres relay.

The agency said now the B sample had confirmed the result of his A sample, his case had been referred to the Court of Arbitration's Anti-Doping Division (CAS ADD).

The court division will consider the finding of an anti-doping rule violation and the disqualification of the British relay team, the ITA said.

If disqualification is the outcome, Canada look in line to be upgraded to silver with China awarded bronze.

Former Olympian and RTÉ analyst David Gillick feels it's inevitable the result will be voided but has sympathy for Ujah's three team-mates.

Speaking on Morning Ireland, he said: "It's always a real interesting case when it comes down to a relay and one of the members fails a drug test. It's looking very likely that a four-year ban will be imposed. It does go to CAS where he can appeal it and he can argue that it was in a supplement he was taking. He has to prove that and in previous cases that has been very difficult for athletes to prove.

"We already saw this year with Shelby Houlihan - top American 5k runner - who failed a drugs test and said that it came from a burrito - and that went to CAS where CAS upheld and she was banned for four years.

"In CJ Ujah's case it's looking very likely he will receive a four-year ban. It's heartbreaking for all the athletes to go to an Olympic Games, put in a stellar performance, come back with a silver Olympic medal and one of your team-mates failed a drug test. Then you are categorised as cheating, you will lose the medal and the result will be void."