Players' agents have been warned their clients may face disciplinary action for derogatory remarks on social media sites such as Twitter.
The Football Association have written to all agents and players' representatives warning them that the players will be held responsible for what goes out in their name.
Some players have previously claimed third parties have posted comments on their Twitter accounts.
The FA have previously advised players about social media and have not extended that to their agents.
The advice says any posts that are over-critical of match officials or that make reference to race, nationality, faith or sexual orientation can result in disciplinary action.
The FA's letter states: "An individual is strictly responsible for any posting on his/her account.
"Participants should take every care to ensure that others do not access their account, as the fact that a posting or comment may have been made by a third party will not prevent disciplinary action being taken against the account holder."
The letter goes on: "Any comments which are improper, bring the game into disrepute or are threatening, abusive, indecent or insulting may lead to disciplinary action. Comments about match officials which imply bias, attack the officials' integrity or are overly personal in nature are considered improper."
Any comments about a person's ethnic origin, colour, race, nationality, faith, gender, sexual orientation or disability "may be considered aggravated and attract a higher disciplinary sanction" warns the letter.
Even re-tweeting another person's post could lead to disciplinary action, while deleting an improper posting will not prevent action being taken.