Simon Cowell said the rendition was ok for a "children's party"

Nathalie Mogg, 18, from Dartford, Kent, and her sister Anne-Marie were shown on Saturday night's episode drinking before being thrown out of their unsuccessful auditions.

Pop Idol judge Neil Fox gave Nathalie a fireman's lift outside after she refused to stop singing while Anne-Marie, 20, was removed by a bouncer.

Ms Mogg told Monday's Daily Express the sisters were teetotal, and had not drunk the liquor but were gargling with it to improve their voices.

'Gargled and swallowed'

"As a singer, you are supposed to gargle with port before a performance to open the vocal chords," she was quoted as saying.

"We didn't have any port, so we took a bottle of Cointreau. We gargled and swallowed it a couple of times, but that was it."

But a spokeswoman from Pop Idol told BBC News Online the pair had been asked by presenters Ant McPartlin and Declan Donnelly whether they were drunk, and denied there had been any unfair editing.

She said the pair had asked the presenters to smell their breath and said they had been drinking Cointreau and tequila.

Ms Mogg, who had sung the Gloria Estefan song Words Get in the Way as her audition piece, also criticised the show's judges: "Musical people like Nicki Chapman and Pete Waterman should be able to hear a good voice."

Her performance was called "panto-ish" by Fox, and Simon Cowell said it was more suitable for a "children's party".

The show attracted more than 6.8 million viewers on Saturday, almost two million more than its first episode on 9 August.