GAA officials have launched an investigation into a vicious assault that left a young referee hospitalised with a broken jaw after a local under-age game in Co Donegal.

Donal Gallagher, a personal trainer and fitness instructor from Termon, a small village north of Letterkenny, was the victim of a serious attack by a spectator following the under-16 Division 3 championship final in which Milford beat Lifford side Naomh Padraig in Convoy on Wednesday. Two Lifford players had been sent off towards the end.

After the final whistle, the young referee, who is in his mid-twenties, received what one spectator described as "a fierce slap on the jaw". A fight ensued and the injured referee was taken to hospital.

He was later discharged but returned after complaining of feeling unwell. Last night he was described as being in a comfortable and stable condition.

He is due to undergo a scan today.

"This is a backward step and does nothing to encourage young people to take up refereeing," said Donegal referees' administrator Frankie Doherty.

"Who would allow a young fella now to go in and be a referee? I don't know where we go from here," he added.

The incident comes in the wake of Tyrone official Martin Sludden being attacked by irate Louth supporters in Croke Park after the Leinster final.

Donegal County Board youth officer Liam McElhinney described it as "a very serious assault" and said that the board was now awaiting the referee's report on the incident.

The injured man is a graduate of the Letterkenny Institute of Technology and runs a sports-injury clinic in Termon.