Rock matriarch Sharon Osbourne launched a scathing attack on David Beckham's alleged 'mistress' Rebecca Loos on a British TV talent show, telling the pretty brunette to "put your knickers on". The England soccer ace's former personal assistant Loos hit the headlines in April 2004 when she claimed she had an affair with Beckham behind his wife VICTORIA's back. Beckham has vigorously denied the claims. Loos teamed up with DIANA, PRINCESS OF WALES' former lover JAMES HEWITT to sing Robert Palmer hit Addicted to Love on ITV1's The X Factor: BATTLE OF THE STARS, in which non-musical celebrities compete in a televised concert. Following Loos and Hewitt's performance on Monday night (29MAY06), Osbourne - close friend of former SPICE GIRL Victoria - made no secret of her opinion of Loos. She said, "A very bad vibe comes from you. You should try doing tomorrow night's show with your knickers on. It will help warm up your voice. "Great song - highly inappropriate. You two are well suited to each other." Following the live broadcast, Osbourne added, "All that pouting and gyrating. I don't understand why they're here."