The Consumer Association of Ireland (CAI) has said people will be "fleeced" by certain Dublin hotels during next weekend's U2 concerts.
Yesterday's Irish Times survey showed Dublin hotels and guesthouses which raised their prices for big rock events.
"I honestly believe it will come back on the hotel industry that they are fleecing customers.
"Hotels in other countries may do the same thing, [increase prices over busy weekends] but not by 100 per cent," said Dermot Jewell, CAI chief executive.
John Power, chief executive of the Irish Hotels Federation, responded: "If the CAI believe this is a rip-off, then they don't know the meaning of the word.
"A rip-off is when consumers are being manipulated or deliberately misled. This is not the case with the hotel industry in Ireland."
Mr Power added that mid-range hotel prices were available in Dublin hotels some months ago. If people booked further in advance they would have received a lower rate.
The Gresham Hotel, which is charging €403.63 for a double room including breakfast for two over the weekend of U2's concert on June 24th-25th compared with €240 the following weekend, did not wish to comment.
Mr Jewell said many tourists had travelled to see U2, and high hotel prices sent the wrong message. He was disappointed by those hotels which "went out of their way" to increase prices significantly.