South Africa wing Aphiwe Dyantyi is facing a long-term suspension after being formally charged with a doping violation.

Dyantyi, who last week denied taking any prohibited substances, was provisionally banned after returning an adverse finding in a test at a Springboks training on July 2 and requested for his B-sample to be tested.

The South African Institute for Drug-Free Sport (SAIDS) said on Friday the B-sample indicated the presence of the same three banned anabolic steroids and metabolites: metandienone, methyltestosterone and LGD-4033.

The 25-year-old has the right to contest the charge in front of an independent disciplinary panel.

Aphiwe Dyantyi's B-sample confirmed the A-sample results - presence of metandienone, methyltestosterone, LGD-4033 >"S1.1A Exogenous Anabolic Androgenic Steroids" & "S1.2 Other Anabolic Agents". Mr Dyantyi has now been formally charged with a doping offencehttps://t.co/Vz633ZSegd
— SAIDS (@drugfreesportZA) August 30, 2019

If found to have breached anti-doping regulations, the 2018 World Rugby Breakthrough Player of the Year could receive a four-year ban.

Speaking last week, Dyantyi maintained his innocence after being made aware of the initial test results.

"I want to deny ever taking any prohibited substance, intentionally or negligently, to enhance my performance on the field. I believe in hard work and fair play," he said in a statement.

"I have never cheated and never will. The presence of this prohibited substance in my body has come as a massive shock to me and together with my management team and experts appointed by them, we are doing everything we can to get to the source of this and to prove my innocence."

Dyantyi has played 13 Tests for South Africa since making his debut against England at Ellis Park in June 2018 but was not included in the Rugby World Cup squad.