Northern Ireland stars Keith Gillespie and George McCartney were involved in a fight on an aeroplane before the ream returned to London following their Euro 2008 defeat in Iceland.
The fight came after the pair were involved in an argument after which punches were thrown before other players were forced to intervene.
“An incident occurred today between team members of the senior Northern Ireland squad of which the president (Raymond Kennedy) and chief executive (Howard Wells) are aware of,” said an IFA statement.
“Both the president and the chief executive will investigate the situation and take appropriate action.”
Northern Ireland’s hopes of making the Euro 2008 finals are fading after Gillespie’s late own goal gave Iceland a 2-1 victory in Reykjavik.