A Football Association statement explained why Mascherano, sent off by referee Steve Bennett for dissent amounting to a second bookable offence at Old Trafford on Sunday, is facing the fresh charge.

The statement reads: "The charge relates to his reaction towards referee Steve Bennett after being sent off against Manchester United on Sunday, March 23.

"He has until 6pm tomorrow to respond. The case will be heard by a regulatory commission on Friday, April 4.

"Mascherano is currently serving a one-match suspension for the sending-off."

The Argentinian midfielder had to be dragged from the pitch by coaching staff and colleagues, after being shown a red card in the 45th minute by Bennett.

The referee had awarded a second yellow following his protests against a caution issued to Reds striker Fernando Torres.

Liverpool boss Rafael Benitez admitted Mascherano made a mistake in refusing to leave the pitch, but felt his sending-off was harsh.

Mascherano can accept or deny the charge and also has the option of requesting a personal hearing.

The 23-year-old's current one-match ban already rules him out of Sunday's Merseyside derby against Everton at Anfield.

But if the charge of improper conduct is upheld then he will also miss Premier League games against Arsenal on April 5 and Blackburn eight days later.

However, any ban would exclude the Champions League quarter-final first and second legs against Arsenal on April 2 and 9.

Benitez had reacted to Mascherano's red card by demanding showdown talks with referees' chief Keith Hackett.

The Spaniard said: "I would like to speak to Keith Hackett, because it is important that we find a solution.

"At Liverpool, we respect the game; we respect the rules and we respect the referee - and it is important to remember that Mascherano was the first Liverpool player to be sent off in the league this season."