Liverpool winger Ryan Babel has been fined 10,000 pounds ($15,860) for comments about referee Howard Webb and the doctored picture he posted on Twitter after his side's FA Cup defeat by Manchester United this month.
Webb, who officiated at the World Cup final last July, awarded United a penalty in the opening minute which Ryan Giggs converted to give the home side a 1-0 win at Old Trafford.
"Social network sites, like Twitter, must be regarded as being in the public domain," the English Football Association's (FA) Roger Burden said in a statement on Monday.
"All participants need to be aware, in the same way as if making a public statement in other forms of media, that any comments would be transmitted to a wider audience. It is their responsibility to ensure only appropriate comments are used," Burden added on the FA website (www.thefa.com).
Babel posted a mocked-up picture of Webb wearing a Manchester United shirt.
"And they call him one of the best referees? That's a joke," wrote the Dutch international, who did not play in the World Cup final that the Netherlands lost 1-0 to Spain, on the social network.
Babel later apologised and was warned by manager Kenny Dalglish to be more careful.
Man United's Rafael charged with improper conduct
Manchester United defender Rafael Da Silva has been charged with improper conduct, the Football Association (FA) said on its website (www.thefa.com) on Monday.
The charge relates to the Brazilian's conduct towards referee Mike Dean following his sending-off in Sunday's Premier League match at Tottenham Hotspur.
The 20-year-old Rafael, who has until Tuesday to respond, was shown two yellow cards by Dean, the second for a trip on Spurs fullback Benoit Assou-Ekotto.
Rafael was incensed with the decision and argued with Dean before leaving the pitch.