(Cover) - EN Showbiz - Natalie Imbruglia thinks Beyonc Knowles songs are hard to sing.

The star is currently a judge on the Australian version of The X Factor, a role she is greatly enjoying. Girl duo Kharizma performed the American superstars hit Single Ladies (Put A Ring On It) on the talent programme this weekend, prompting Natalie to discuss Beyoncs back catalogue. She loves listening to the R&B star, and is constantly amazed by her vocal range.

They are one of my favourites in the competition, Natalie told Australian radio programme The Kyle and Jackie O Show, while discussing the groups performance. It is such a hard song picking a Beyonc song.

After hearing Kharizmas version, Natalie admitted she thought they could have done better. She said the girls performance was strong to begin with, but something weird happened later which spoiled it.

The 35-year-old has previously said she has no qualms about telling hopefuls the truth on the programme. Although she doesnt relish delivering bad news, Natalie insists there is no point in sugar-coating things if an act has underperformed.

Im a smiling assassin, she laughed. (C) Cover Media