Simon Cowell has threatened to sack warring X factor judges, Sharon Osbourne and Dannii Minogue if they can’t learn to put up with one another on the show.

Last years show was plagued by rumours of a massive feud between the pair, and this year things aren’t looking any more pleasant.

“It’s nearly contract time again. Sharon said she doesn’t want to come back with Dannii – and Dannii said she doesn’t want to work with Sharon,” an insider told The Sun.

“But Simon has banged both their heads together and told them, ‘If you don’t shut up – I can replace you both’. They don’t have to be best friends – but they do have to work together.”

However, the source added: “Bosses know that viewers were hooked on the backstage battles between Sharon and Dannii and they want to keep them both on board – it makes for very interesting TV.”