Athletic Bilbao defender Yeray Alvarez says he has been provisionally suspended for “unintentional” use of a banned substance used to treat alopecia.

The 30-year-old Spaniard failed a doping test after Bilbao’s 3-0 defeat by Manchester United in the Europa League semi-finals on 1 May.

He said he had been taking the medicine as part of his treatment for hair loss after being diagnosed with testicular cancer in 2016.

Alvarez, who has made 257 appearances for the La Liga club, said he “couldn’t believe it” when he was informed of the test, adding it was a “very hard blow” to take.

“After studying the case, we have established that I tested positive because I unintentionally took a hair loss prevention medicine containing a banned substance,” Alvarez said in a social media post, external.

“The disciplinary procedure is currently under investigation and subject to confidentiality so I am provisionally suspended and am not authorised to make any further public statements.

“I very much regret this situation but, with the support of the club, I am working on my defence in the belief that I will be able to return to the field of play as soon as possible.”

Uefa has told BBC Sport it will not comment on the case until a final disciplinary decision has been made.

An Athletic Bilbao statement said: “Athletic Club wishes to express its full support for Yeray Alvarez at this time and its complete confidence in the bodies charged with resolving the case.

“Once the proceedings are concluded, Yeray Alvarez and Athletic Club will offer all the pertinent and necessary explanations.”