Monaghan won 2-1 but before the game the FAI received information about unusual betting interest on a penalty being awarded.
Shelbourne manager Alan Mathews told extra-time.ie: “Fran Gavin [Airtricity League director] came into the dressing room before the game to tell us that there were irregular betting patterns on the game.”
Gavin also informed Monaghan boss Roddy Collins. Collins said he had already been made aware of the issue before the game, when a girlfriend of one of his players who works in a bookmaker texted the player.
The FAI have passed the information on to UEFA, who will now decide the next step.
Meanwhile, in the Airtricity First Division, Longford beat Monaghan 1-0 on Saturday, Noel Haverty’s first-half goal proving decisive at Flancare Park.
Finn Harps went down 2-1 at home to Athlone Town.
Stephen Relihan gave Town the lead before Kevin McHugh equalised.
Brian McCarthy grabbed a 62nd-minute winner.