The Sun reports that Northern Ireland stars Keith Gillespie and George McCartney came to blows after Wednesday night's 2-1 defeat to Iceland.
The pair clashed on the plane before their flight and were separated by cabin crew.
An eyewitness on the flight said: "I was walking down to my seat and I saw a commotion in the middle of the plane.
"There were players involved and punches thrown, but it was over almost as quickly as it started.
"A flurry of other players waded in and calmed everything down.
"Nigel Worthington was further up the plane, and senior cabin crew went down and had a word with the players involved."
The fight was reported to Worthington and the IFA have confirmed they will investigate the clash.
A statement said: "An incident occurred between team members of the senior Northern Ireland squad of which the president (Raymond Kennedy) and chief executive (Howard Wells) are aware of.
"They will investigate the situation and take appropriate action."