Liverpool defender Mamadou Sakho has been handed an initial 30-day suspension while Uefa investigate his doping violation.
The France international is facing a lengthy ban after he accepted the findings of a drug test taken after the Europa League clash with Manchester United on 17 March. The 25-year-old is thought to have tested positive for a type of fat burner.
Sakho decided not to request for a B sample to be tested ahead of Tuesday's (26 April) deadline. Liverpool have already withdrawn the defender from selection but Uefa have now confirmed his season is over.
"Disciplinary proceedings have been instigated against Liverpool FC player Mamadou Sakho, following the Uefa Europa League round of 16 second-leg match between Manchester United FC and Liverpool FC (1-1), played on 17 March," a statement from Uefa read.
"The proceedings relate to a violation of the Uefa Anti-Doping Regulations, after the player failed a doping test at the above mentioned match. The player did not request the analysis of the B sample. Uefa has now suspended the player provisionally for 30 days until a final decision is taken by the Uefa Control, Ethics and Disciplinary Body. The date of the disciplinary hearing will be announced at a later stage."
Liverpool take on Villarreal in the first leg of their Europa League semi-final on Thursday. Speaking ahead of the match, manager Jurgen Klopp said of the Sakho situation: "I think what they are all doing is collecting all the information to clear the situation as much as possible.
"We have to wait for the next step, it is not as if we can force anything, we have to wait. We did what we thought was right, that is all, there is nothing else to say."