Credit: Jon Kopaloff/FilmMagic

David and Victoria Beckham are slamming the latest cover of tabloid In Touch, which claims that he cheated on her with a $10,000-a-night hooker.

A rep for the two tells UsMagazine.com that the allegations -- which include a threesome and unprotected sex -- "are completely untrue and totally ridiculous, as the magazine was clearly told before publication.

"Sadly we live in a world where a magazine can print lies and believe they can get away with it," adds the rep. "We are taking legal action against the magazine."

A source tells Us that David, 35, and Victoria, 36, will definitely "fight this. They're fed up with people trying to tear them apart. Their love is strong."

The two, who have been wed for 11 years, have three sons, Brooklyn, 11, Romeo, 8, and Cruz, 5.