Dannii Minogue and Louis Walsh have hit out at their fellow judges Cheryl Cole and Simon Cowell for using ‘hidden professional backing singers’ to drown out their acts’ own voices. The News Of The World reports that “top producers and singers” are brought in to record parts of the “live” performances.

The paper says that both Louis and Dannii have slammed the practice, saying it gave Simon Cowell and Cheryl Cole an unfair advantage.

An X Factor show source told the newspaper: “Louis and Dannii are furious. In their view the backing vocals on acts mentored by Cheryl and Simon are much louder and stronger than their acts. The public should be voting on who is the best singer, not who has the best production and backing vocals.”

The X Factor’s vocal coach Savan Kotecha confirmed that singers and producers were brought in to mix and prepare the backing tracks for the live shows, however insisted all of the acts have the same treatment. A show spokesman said: “Acts are always treated fairly. Chorus vocals simply depend on the arrangement of the song being performed.”