The former promotional manager of family musical trio Crystal Swing has hit out at the band after they dropped him.

Hugh O'Brien, who runs Sky television channel Rural TV, said the band had "lost the run of themselves and are trying to be something they are not".

O'Brien's decision to put the hit video 'He Drinks Tequila' on his channel and later on YouTube catapulted the Co Cork trio to fame. O'Brien then began to look after publicity for the band.

He said that the band, consisting of Mary, Derek and Dervla Burke, had been changed by their sudden rise to fame, which has seen them appear twice on The Late Late Show and once on the Ellen DeGeneres talk show in the US.

"They are thanking every radio station and every paper – everyone, except me now. They are not talking anymore about where they came from or who got them there. I was the one who got them everywhere they are now. I got them off the ground," he said.

"They are losing the run of themselves, forgetting who originally got them on The Late Late Show, The Sean Moncrieff Show, The Ellen DeGeneres Show. No record label would go near them until I started looking after them and doing all their publicity for them.

"They have made a lot of foolish choices, and ignoring how they started is one of them. Small things, right down to Derek performing 'The Hucklebuck' on The Late Late Show and on Ellen DeGeneres, were my idea."

Crystal Swing recently sold out the Opera House in Cork, but O'Brien did not receive an invitation to the show after being cut off by the band. He also said the group's commercial appeal was showing signs of wearing off.

"They are not selling tickets anymore, and sales will only continue to go down. I managed to get them onto the charts, get their name out there. They are no longer on the charts. No record label would go near them until I started looking after them and doing all their publicity for them.

"It could turn out that they will easily go back to being the way they were before – a small-time band – only they happened to have a few moments of glory."

O'Brien said most of the blame for the band's new direction was attributable to Mary, the mother of Derek and Dervla.

"Mary is the driving force behind the band and she is pulling the strings so I would say this is her doing," he said.

O'Brien's replacement as promotional manager, Hugh Rodgers, dismissed his predecessor's criticism.

"We don't consider that there is any animosity there," he said. "Hugh O'Brien was there to do all the things he did with the 'Tequila' track, and beyond that I don't know."

Mary Burke was unavailable for comment this weekend.

O'Brien is now managing 10-year-old Simon Donegan (inset, left) from Donegal who has already recorded his own songs, and who O'Brien is now tipping to be the next Crystal Swing.