Paris St Germain say they will "take any action they deem neccessary" after Joey Barton used social networking website Twitter to liken defender Thiago Silva to an "overweight ladyboy''.
The Marseille midfielder, on loan from Queens Park Rangers, fired a series of verbal volleys at the Brazilian defender during PSG's Champions League quarter-final first leg draw with Barcelona on Tuesday night.
Barton was irked after Silva had referred to him in a press conference leading up to the clash with Barca, and questioned whether the player was "pre-op or post-op [transsexual]''.
On Wednesday, PSG posted a statement on their official website that criticised Barton and said they may take action against him.
"In the last few hours, on social networks, unacceptable remarks have been made by Olympique Marseille player Joey Barton against Paris St Germain player Thiago Silva," it said.
"These attacks are serious and go beyond mere verbal jousting. The directors of the club, the players and the coaching staff are supportive of Thiago Silva and cannot accept such statements.
"They reaffirm their unwavering commitment to the values of respect that should govern our sport. Thiago Silva and Paris St Germain reserve the right to take any action they deem necessary.''
PSG have taken issue with a series of tweets against the player which began to appear on Barton's account from Tuesday afternoon.
Barton originally tweeted: "Thiago Silva. That the same p**** thats been injured all season. Another over rated Brazilian. Sort your hamstrings out FatBoy...''
The Liverpudlian was responding negatively to comments from Silva ahead of the tie at the Parc des Princes, which finished 2-2 ahead of next week's second leg at the Nou Camp.
He continued tweeting during the game, adding: "Have to take back what I said about Thiago Silva being over rated today. Been immense tonight. Still looks like a overweight ladyboy though!
"2 questions for Thiago Silva. Firstly, Why are YOU talking about ME, in your press conference before PSG v Barca? Very strange. Secondly, Are you Pre-Op or Post-Op? #transsexual #thiagosaladyboy
"Baffles me, which way he's going. Is he a man changing to a woman or a woman changing to a man? Can't work it out.''
Speaking to L'Equipe on Monday, Silva had said: "There is a Marseille player, I cannot remember his name, an Englishman, who has said bad things about Neymar and Brazilian football, and also about (David) Beckham and (Zlatan) Ibrahimovic.
"Because no one is talking about him, it seems it is fun for him to criticise great players for people to know he exists.''
Marseille revealed late on Wednesday that Barton had agreed "to immediately cease posting online any derogatory statements regarding Thiago Silva", with the club issuing a statement insisting they, and Barton were "keen to apolgise" for the exchanges.
Information from the Press Association was used in this report