London - Liverpool manager Jurgen Klopp faces a touchline ban or a fine after being charged by the Football Association (FA) for comments he made about referee Kevin Friend after his side's Premier League clash at West Ham on February 4.

Klopp intimated after the 1-1 draw that Friend's second half performance had been affected by an assistant referee's mistake for Sadio Mane's opening goal.

Mane's goal stood at the London Stadium despite James Milner being clearly offside in the build-up before Michail Antonio's equaliser cost Liverpool two points in the title race.

"As a human being, if I know I have made a big mistake in the first half, I don't want to open the gap any more," Klopp said after the game.

"Referees are obviously human beings, and I understand that, but I didn't during the game because I had no clue that our goal was offside."

The FA confirmed Klopp had been charged for questioning "the integrity" of the match official.

"Jurgen Klopp has today been charged with a breach of FA Rule E3," said the FA in a statement.

"It is alleged that comments he made in a post-match interview following Liverpool's league game against West Ham United on February 4, 2019, breached Rule E3(1) as they questioned the integrity of the match referee and/or implied bias.

"He has until 6pm on February 18, 2019 to respond to the charge."

Liverpool are second in the Premier League behind Manchester City only on goal difference and with a game in hand.

However, if Klopp is found guilty he could be banned from the touchline when they travel to Manchester United on February 24.