Luis Suarez has apologised for biting Branislav Ivanovic and admitted his actions were "inexcusable".
And Liverpool have criticised their controversial striker with manager Brendan Rodgers branding it "unacceptable" and managing director Ian Ayre saying he had let the club down.
Suarez bit the Chelsea defender on the arm in Sunday's 2-2 draw at Anfield and escaped unpunished for it, going on to score his side's injury-time equaliser.
Rodgers earlier claimed not to have seen it but said he would launch an internal inquiry into the incident and had warned Suarez that no player is bigger than the club.
And Liverpool's 30-goal top scorer has accepted he was in the wrong, tweeting:
I'm sad for what happened this afternoon, I apologize Ivanovic and all football world for my inexcusable behaviour. I'm so sorry about it!!— Luis Suarez (@luis16suarez) April 21, 2013
In a statement on Liverpool's official website, Suarez added: "I am deeply sorry for my inexcusable behaviour earlier today during our match against Chelsea. "I have issued an apology and have tried to contact Branislav Ivanović to speak to him personally. I apologise also to my manager, playing colleagues and everyone at Liverpool Football Club for letting them down."
Rodgers added: "Having reviewed the video footage and spoken to Luis, his behaviour is unacceptable and I have made him aware of this." Ayre said: "Luis has made an unreserved apology for his actions today. His behaviour is not befitting of any player wearing a Liverpool shirt and Luis is aware that he has let himself and everyone associated with the club down. We will deal with the matter internally and await any action from the FA."
The FA are still expected to take action against Suarez, who was nicknamed "the cannibal of Ajax", after biting an opponent, PSV Eindhoven's Otman Bakkal, during his time in Holland.
The controversial striker was given an eight-match ban last season when he was found guilty of racially abusing Manchester United defender Patrice Evra.
Former Liverpool captain Graeme Souness had called his actions "embarrassing" and said he is in the last-chance saloon at Anfield now.
And Gary Lineker, the top goalscorer in the 1986 World Cup, called on the PFA to remove Suarez from the shortlist for the Player of the Year award.