Jürgen Klopp has said Liverpool have taken the correct steps by not considering Mamadou Sakho for selection while Uefa investigates his failed drug test. The Liverpool defender is facing a lengthy suspension from the game having decided not to challenge the results of his A sample given at Old Trafford last month.

The France international has accepted the findings of a drug test taken after the Europa League tie at Manchester United on 17 March, which is understood to have revealed evidence of a fat-burning substance, and did not request that a B sample was examined before the Uefa deadline on Tuesday.

Liverpool have refused to comment on the defender’s decision, insisting it is a private matter at this stage, and Sakho will remain unavailable for selection despite not being formally charged by Uefa so far. European football’s governing body has also insisted the process remains confidential.

Klopp’s squad arrived in Spain on Wednesday for their Europa League semi-final first leg against Villarreal without their in-form £19m defender, who joins the injured Divock Origi, Emre Can and Jordan Henderson in missing the game.

The Liverpool manager said: “I think what they are all doing now is collecting information to clear the situation as much as possible. Then we have to wait for the next steps. It is not that we could do anything or we could not force anything, we have to wait. Until now we did what we thought was right. There is nothing else to say.”

Sakho’s acceptance of the A sample’s findings may hasten the disciplinary process, meaning a suspension would start earlier than had he challenged the results. He is expected to present mitigating evidence to Uefa as the investigation proceeds.

His team-mate Kolo Touré was handed a six-month ban by the Football Association for failing a drugs test while at Manchester City in 2011 as a result of taking his wife’s diet pills. A similar punishment would cost Sakho his place at the European Championship to be held this summer in France.