A male British Olympic athlete was supplied with banned drugs by an American therapist who is facing 10 years in jail, according to court papers filed in New York.
In May, Eric Lira became the first defendant to be charged under a new US law introduced in the wake of Russia's state-backed doping scandals.
He pleaded guilty to supplying performance-enhancing drugs to Olympic athletes.
But a sentencing document filed in the Southern District of New York has given details of other athletes and coaches implicated in the case, with an unnamed British competitor also referred to.
"Lira separately met with a third Olympic athlete who competed on behalf of the United Kingdom ('Athlete-3') multiple times in the Summer of 2021 for the purpose of providing him with PEDs [performance-enhancing drugs]," claims US attorney Damian Williams, in the document, which has been seen by the OceanNewsUK.
As revealed by the Times, the case is now being investigated by the Athletics Integrity Unit (AIU).
The AIU declined to comment. UK Athletics also declined to comment, but is not believed to have been informed about the matter by the AIU.
Lira was found to have supplied drugs to Nigerian sprinter Blessing Okagbare, who last year was banned from athletics for 11 years.
The 34-year-old was expelled from the Tokyo Olympics just before the women's 100m semi-finals after it emerged she had tested positive for human growth hormone in an out-of-competition test in Slovakia before the delayed 2020 Games.
The court documents also state that: "Lira likewise provided drugs to an athlete competing on behalf of Switzerland in advance of the Olympic games ('Athlete-2') in the Summer of 2021, and discussed with an intermediary the detectability on drug tests of one of the prohibited drugs that Lira had provided to Athlete-2.
"In short, Lira travelled across the United States to deliver and/or administer various drugs to various Olympic athletes, all with the calculated aim of impacting the outcome of the Tokyo Olympics."
In a separate document, federal prosecutors also charged two American coaches, claiming they worked with Lira to provide drugs for athletes from Nigeria, Switzerland and the UK ahead of the Tokyo Olympics.
Lira was charged under a 2020 law named after Russian whistleblower Grigory Rodchenkov, the former head of Moscow's anti-doping laboratory who helped expose the country's state-sponsored doping regime.
Williams said in a federal court the case was a "watershed moment for international sport".
The Rodchenkov Anti-Doping Act enables US authorities to prosecute individuals involved in "doping schemes for the purpose of influencing international sports competitions" including those who have not previously been governed by sport anti-doping laws.
