Southend United have revealed Liam Dickinson, Ryan Hall and Kane Ferdinand were guilty of breaching club discipline in an incident at the team hotel on Friday night.
The Shrimpers lost 1-0 at Morecambe in a game which striker Dickinson and midfielder Hall started.
Boss Paul Sturrock did not learn of the unspecified indiscretion until after the match.
The club said it would deal with the matter internally.
"The manager learned after Saturday's match at Morecambe that there had been a breach of discipline on Friday night at the team hotel by three members of his squad," read a club statement.
"The individuals were Liam Dickinson, Kane Ferdinand and Ryan Hall whose conduct was unacceptable to the club's management.
"The manager and board of Southend United require their players to behave professional at all times in the best interests and success of the club.
"It is now an internal matter and no further comment will be made."