Sharon: Dannii was 'deeply irritating'

She said: "She [Dannii] clearly felt s***ging Simon gave her vicarious power and it was so immature, not to mention deeply irritating to deal with."

Sharon alleges Dannii became bossy and overbearing and acted inappropriately behind the scenes doing things like "sticking her tongue in Simon's ear", which made Sharon and fellow judge Louis Walsh feel uncomfortable.

In her autobiography, 'Unbreakable', Sharon wrote: "The closer she got to Simon, the more I felt she started telling the producers what to do. Suddenly, from being the new girl, she was saying, 'This isn't right,' and, 'Simon doesn't like it this way.'

"Meanwhile the antics behind the screen had gone up a gear, with her sticking her tongue in Simon's ear and giggling like a bloody teenager as Louis Walsh and me stood there like a couple of gooseberries.

"For me, it made her so unbearable to work with that I just couldn't take it. It was horrible. My stomach was constantly knotted with anxiety about it and as each show loomed I would wake up and think,

'Oh God, I have to spend the day sitting alongside her again. ' "

After an unsuccessful meeting with the executive producer Richard Holloway which didn't help resolve differences between Sharon and Dannii she turned to media mogul Simon asking him to choose which girl he wanted to keep but he was not willing to pick.

Sharon explained: "I was here to fight my corner ... I walked in, gave him a kiss on each cheek and launched straight in. 'I can't take it anymore. It's her or me,' I said.

"His expression remained impassive. Simon is used to spats between the women in his life and clearly takes it all in his stride. 'I'm not going to make that choice, Sharon. I'd like you both to stay.' "

Sharon returned to 'The X Factor' judging panel this year and is joined by Gary Barlow, Nicole Scherzinger and Louis.

Meanwhile, Simon - who is a judge on 'The X Factor' USA - is expecting his first child with girlfriend Lauren Silverman.