Cowell takes pop at X Factor judges

Simon Cowell is back with a vengeance on the X Factor USA judging panel, following a bout of illness.

Louis Walsh kept the TV mogul's seat warm for the Kansas auditions of the American version of the singing competition while Simon was suffering from bronchitis, where he bonded with fellow judges Britney Spears, Demi Lovato and LA Reid.

Simon - who returned for the San Francisco auditions - proved that his sharp tongue had not disappeared when he tweeted: "Unfortunately Britney & Demi are now known as the gruesome twosome. V happy to be back - Demi more annoying than ever, Britney has grown claws!"

Britney replied: "And I'm not afraid to use them!"

Earlier, the Toxic singer had joked that they were planning to be tough on Simon.

"Simon better, it's adorable! I'm glad @SimonCowell is feeling better. I know @ddlovato, @LA_Reid & I aren't cutting him any slack today!" she wrote.

And she added: "We'll miss u Louis! Louis - I will miss you new friend!!"