The promoters of the Electric Picnic say no further tickets will be going on sale for this year's event.
The music and arts festival - which is marking its 10th anniversary - is taking place this weekend in Stradbally in Co Laois.
A capacity crowd of 35,000 will be attending the three day event - which is being headlined by acts including Fatboy Slim and Arctic Monkeys.
Melvin Benn - from promoters EP Republic - is warning that counterfeit tickets will be detected:
