Liverpool defender Mamadou Sakho has been suspended by the club pending an investigation by UEFA into a possible anti-doping rule violation.
The decision, taken in conjunction with the player, means the France international will not be considered for selection until the matter is resolved.
A Liverpool statement read: "Yesterday, Friday 22nd April 2016, 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.
"There will be no further comment at this time."
Sakho, who joined Liverpool in August 2013 from Paris Saint-Germain, has been a regular for the club this season, making 22 Premier League appearances and scoring in their 4-0 derby win over Everton in midweek.
He also grabbed a vital goal as Liverpool completed a remarkable comeback to beat Borussia Dortmund 4-3 in the Europa League quarter-finals on April 14.
His omission from the team means Sakho will not feature in Saturday's game with Newcastle United and puts his participation in the remainder of Liverpool's Europa League campaign and Euro 2016 in considerable doubt.
Reports in France suggest Sakho tested positive for a 'fat-burning substance' following Liverpool’s 1-1 Europa League draw at Manchester United on April 17.
The 26-year-old has until Tuesday to request the testing of a B sample.
Sakho's Liverpool team-mate Kolo Toure was banned for six months in 2011 after taking slimming tablets belonging to his wife.
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