South Africa wing Aphiwe Dyantyi has been given a four-year ban after testing positive for performance-enhancing substances.

Dyantyi, who was named the World Rugby Breakthrough Player of the Year in 2018, pleaded guilty but says he did not knowingly take a banned substance.

The South African Institute for Drug-Free Sport said Dyantyi's denials had not met the burden of proof.

The ban will run until August 2023. The 25-year-old has the right to appeal.

Dyantyi made his debut for South Africa against England in June 2018 and has 13 caps in total.

The wing, who plays for the Golden Lions in Johannesburg, was provisionally suspended in August 2019 after a first doping test was found to contain multiple anabolic steroids.

His first sample tested positive on 2 July that year; he then requested his second sample be tested, and that also came back positive.

Dyantyi claimed he drank from the bottle of a friend during a gym session two days before the urine sample was taken.

After confirming his ban, the South African Institute for Drug-Free Sport said it wanted to remind athletes to "exercise caution when using sports supplements" and evaluate the risk of products which claim to help gain muscle quickly.