PFA chief Gordon Taylor has questioned the wisdom of football clubs banning their players from using Twitter.
"It is not necessarily good enough to say 'no, we don't have it at all'," said Taylor.
"Every person has got the right to speak in public so long as it is their own point of view and it does not reflect badly on their employers, the game or other personalities in the game.
"If it is defamatory then it can then be used against that person in a legal manner for compensation."
"It is not an easy thing, but used in the right way it can help with relationships between players and supporters," he added.
Manchester United's Rio Ferdinand is one of the most popular players on the social network, with around 1.3m followers.