LONDON • Liverpool have sidelined Mamadou Sakho after being notified the defender is being investigated over a failed drug test.

The alleged offence relates to the English football club's Europa League round-of-16 second leg at Manchester United last month and is believed to concern a fat-burning substance.

The 26-year-old centre-back is believed not to have known the composition of the weight-loss supplement and has informed the club he acted in good faith.

A Liverpool club statement said: "Yesterday, a formal communication was received from Uefa stating that they are investigating a possible anti-doping rule violation by Mamadou Sakho. The player will respond to Uefa on the matter.

"The player is currently not subject to any playing suspension. However, the club, in consultation with the player, has decided that, while this process is followed, the player will not be available for selection for matches."

The France international, whose participation at Euro 2016 will now be in doubt, is highly likely to ask for his B sample to be tested, with the deadline for that request set for Tuesday.

It is understood that, after a discussion between the club's owner, Fenway Sports Group, the manager, Juergen Klopp, and Sakho himself, it was decided the centre-back should not play in the immediate future, even though he is still eligible for Premier League matches and Thursday's Europa League semi-final first leg at Villarreal.

Klopp was reluctant to comment on the matter before yesterday's

2-2 Premier League home draw with Newcastle, courtesy of goals from Daniel Sturridge and Adam Lallana. Papiss Cisse and Jack Colback scored for the away team.

He told Sky Sports News: "I could but I think you know already.

"It makes more sense it's told in the perfect words, not by me, so that's the official statement of the club.

"In respect of the situation and the player, I should not say anything more. I don't know enough to say more."

If Sakho is unable to prove his innocence, it would be a significant blow to Klopp. The former Paris Saint-Germain player has formed a solid partnership alongside Dejan Lovren in recent weeks and has also scored twice in his last three outings for Liverpool.

Sakho's Liverpool team-mate Kolo Toure was banned for six months for taking a fat-burning diet pill in 2011.

THE GUARDIAN, AGENCE FRANCE-PRESSE