Liverpool’s Mamadou Sakho faces a lengthy ban from football after deciding not to challenge the results of a failed drugs test.

The France international is understood to have opted not to request a test of his B sample ahead of Tuesday’s deadline after initial results revealed traces of a fat-burning substance.

Liverpool v Newcastle United - Premier League

Sakho watches from the stands after his failed test was announced

Sakho, 26, was left out of the Liverpool squad at the weekend after UEFA flagged up a potential violation as a result of a test following the club’s Europa League tie at Manchester United last month.

Although Sakho is still currently eligible to play, Liverpool said he and the club had decided he would not be selected until the issue of the failed test had been resolved.

The ¬£18m defender was not on the team’s Wednesday lunchtime flight to Spain, where they are taking on Villarreal¬†in the Europa League semi-final first leg.

Sakho could be banned for up to two years, but with mitigation his time on the sidelines might be reduced to six months.