On last nights X Factor show we saw the three judges being assigned their categories for the bootcamp and final. Needless to say Louis Walsh wasn’t too pleased at receiving the groups and was even less pleased when fellow judge, Simon Cowell, phoned up to gloat.

However after the cameras stopped rolling and the judges met backstage they kicked off into one of their biggest rows yet.

A source said: “At first everyone thought they were messing around - but it quickly became serious. Simon and Louis were screaming insults at each other. At one stage it looked like it was getting out of hand. But crew members stepped in and calmed them down.”

The feud continued last night as furious Louis, 54, told The People: “Simon is not as good as Simon thinks he is.

“Me and Sharon Osbourne know more about the music business. Simon Cowell is in the Simon Cowell business. He’s too busy doing American Idol and running around the world to concentrate on the music.”

Louis, who will be guiding bands like the Dollyrockers and Eton Road in the knockout stages, vowed to stop at nothing to beat Mr Nasty Simon, 46. He said: “I know about groups - I had Boyzone and I had Westlife and Girls Aloud. I’m absolutely confident I can beat him.

“Look what happened when I had the groups before. G4 are on their third album now.

“But where is Steve Brook-stein? Has anyone seen him? There’s a reward for anyone who can find him.”

Our source said: “Louis couldn’t stand Simon being so full of himself and has declared war. He is determined to watch Simon laughing on the other side of his face.

“He might not have wanted the groups but he knows he can make the best of it. He’s one of the most successful managers in the country and has had phenomenal success with groups.”

In the immortal words of Sharon Osbourne “Let the battle begin!”