Chelsea have confirmed they have contacted the Football Association after winger Mykhailo Mudryk returned a negative result in a routine urine test.
The Ukraine international, who has made 15 appearances for the Blues this season, denies knowingly taking banned substances.
Chelsea’s statement read: “Chelsea Football Club can confirm that the Football Association has recently contacted our player Mykhailo Mudryk regarding an unpleasant finding in a routine urine test.
“Both the club and Mykhailo fully support the FA testing program and all our players, including Mykhailo, are tested regularly.
“Mykhailo has categorically confirmed that he has never knowingly used banned substances.
“Both Mykhailo and the club will now work with the relevant authorities to establish what caused the adverse finding.
“The club will not comment further.”
The Athletic, citing multiple sources, reported that Mudryk tested positive for meldonium after playing for Ukraine in November. Meldonium can help an athlete recover after intense exercise and was added to the World Anti-Doping Agency (WADA) banned list in January 2016.
Mudryk said on social media: “I can confirm that I have been notified that a sample I provided to the FA contained a banned substance.
“This came as a shock as I have never knowingly used banned substances or broken any rules and I am working closely with my team to investigate how this could have happened.
“I know I haven’t done anything wrong and hopefully I’ll be back on the pitch soon. I can’t say more now because of the confidentiality of the process, but I will as soon as I can.”
Mudryk, who has missed Chelsea’s last five games with the club citing illness, joined the west Londoners from Shakhtar Donetsk last January for a fee that could be as high as £88m. He has struggled to hold down a regular place in the first team and, this season, has played largely in the second-string team that has competed in cup matches.