We're surprised it took this long to be honest, but the first proper reports of behind-the-scenes aggro have been emerging from The X Factor.

And even less surprisingly, it seems that old enemies Cheryl Fernandez-Versini and Louis Walsh are at the centre of the problem.

The Sun newspaper claims that the atmosphere on set on the ITV talent show is "toxic", with the pair refusing to speak to each other off camera.

A source said: "The atmosphere has become toxic — she hates him with a real passion and it shows.

"It's no secret that Cheryl didn't want Louis on the panel, but since then he has been lording his victory and takes every opportunity to knock her.

"On the panel he has repeatedly slapped her down, and she has given him some poisonous stares in return.

"If looks could kill, Louis would be a dead man."

And insiders are reported to fear that the feud could boil over and damage the show.

"The tension between them became painfully obvious when they clashed at boot camp," the mole continued.

"They made Dannii Minogue and Sharon Osbourne look like best pals. This is a pressure cooker and it's only a matter of time before someone explodes."