A teenage boy was arrested after an incident at a League of Ireland match in Longford on Friday night.
Gardai are investigating the disturbance caused by a small number of away fans at the match between Longford Town and Bray Wanderers at Bishopsgate.
A male in his late teens was arrested under the Public Order Act.
A spokesperson for the FAI said: "The League of Ireland and the FAI strongly condemn the behaviour of a small number of spectators in the away section at the Longford Town v Bray Wanderers game on Friday night.
"We are now working closely with the Gardai and both clubs to ensure those responsible are held accountable for their actions. The FAI has a zero tolerance policy towards this type of behaviour and will take further action once the Garda investigations are concluded.
"The safety of all players, fans and stewards is of paramount importance to the League of Ireland and the FAI."
The game ended 1-1 between the First Division sides.
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