PFA deputy chief executive Mick McGuire said: "We totally support the club's action in not allowing players to write books while they are still pursuing their careers. We have seen over the last few weeks the difficulties which can arise by trying to write what you consider to be a true reflection of events.
"Unfortunately, you can leave yourself at the mercy of people who gain an advantage out of the book being successful, which can mean sensationalising certain aspects.
"The approach Manchester United are taking now is a sensible one, although I cannot see how they can extend that to newspaper articles.
"When you have as many high profile players as them, who are asked for their opinions on a range of topics by a range of people, I'm not sure how it could be enforced.”