LeRoy Bell LeRoy Bell

Fox revealed that the vocals on X Factor's group performances are pre-recorded, according to The Wrap.

"For the group ensemble performance, the vocals are pre-recorded to allow acts to concentrate on preparing for their own live competitive performances on Wednesdays — this is also no different to what other competition shows do for ensemble performances," a show rep said. "All survival songs are performed live, with just a backing track."

Catch up on X Factor news

During Thursday's night's broadcast, singer Leroy Bell was heard singing before he held his microphone to his face, leading to the controversy. Regardless, he made it through to the next round.

Watch the clip of him "singing" below: