Amir Khan has been banned from all sport for two years after it was revealed that he failed a drugs test after his fight with Kell Brook last year.
The two long-time rivals finally agreed to square off in February 2022 with Brook dominating before recording a sixth-round stoppage in Manchester.
Khan announced his retirement soon after that defeat, and has kept to that decision despite briefly hinting that he was considering remaining in the sport.
However, it has now been revealed that Khan tested positive for the banned substance ostarine on the back of losing to Brook, and has subsequently been banned from competing for two years.
The 36-year-old has been able to prove that the indigestion of the drug was unintentional, but accepted the punishment handed to him by UKAD.
In a statement, UKAD said: "Professional boxer and Olympic medallist Amir Khan has been banned from all sport for two years following Anti-Doping Rule Violations (ADRVs) for the presence and use of a Prohibited Substance.
"On 19 February 2022, UK Anti-Doping (UKAD) collected an In-Competition urine Sample from Mr Khan after his fight against Kell Brook at the Manchester Arena. Mr Khan's Sample returned an Adverse Analytical Finding (AAF) for ostarine.
"Ostarine is a selective androgen receptor modulator (SARM). The substance is listed on the World Anti-Doping Agency's (WADA) 2022 Prohibited List as an anabolic agent and is prohibited in sport at all times.
"UKAD notified Mr Khan of the AAF on 6 April 2022 and that he may have committed ADRVs under the 2021 UK Anti-Doping Rules (ADR). UKAD issued him with a Provisional Suspension from all Code-compliant sport on the same date."
"On 20 July 2022, UKAD charged Mr Khan with the commission of two ADRVs: under ADR Article 2.1 (Presence of a Prohibited Substance); and ADR Article 2.2 (Use of a Prohibited Substance). Mr Khan accepted the violations charged but maintained that his ingestion of ostarine was not 'intentional' (a term with a specific meaning set out at ADR Article 10.2.3).
"As a consequence his case was referred to the National Anti-Doping Panel to be considered by an independent tribunal. Mr Khan's case was heard by the independent tribunal on 24 January 2023 and in its written decision dated 21 February 2023, the panel found both violations proved, concluded that Mr Khan had established that they were not 'intentional' within the meaning of ADR Article 10.2.3 and imposed a two-year ban on him.
"Mr Khan's two-year ban is deemed to have commenced on 6 April 2022 (the date his Provisional Suspension was imposed) and will expire on 5 April 2024."
Khan's showdown with Brook was his first outing in over two-and-a-half years, while Brook has recently gone back on his decision to retire and will return later this year.