Millwall defender Alan Dunne has been fined £2,000 after admitting a charge of improper conduct in relation to comments he made on Twitter.
The 29-year-old retweeted a critical comment of referee Jon Moss' performance following his sending off during the 6-0 rout at the hands of Birmingham last month.
Millwall manager Kenny Jackett issued a written warning to all squad members in the wake of Dunne being charged.
However, the Lions boss stopped short of banning his players from using the social networking tool.
Dunne was found guilty of a breach of Football Association rule E3.