Hollywood star Cameron Diaz (search) plans to sue a British tabloid newspaper over a story suggesting she was having an affair with a married man, her lawyers said Friday.

Attorney Simon Smith said Diaz had instructed his firm, Schillings, to start libel proceedings against the publishers of The Sun (search). Smith said lawyers hoped to file a writ by Monday.

The Sun said it would not comment until it had received legal papers.

On Thursday, The Sun carried a story claiming Diaz, who is dating singer Justin Timberlake (search), had a close relationship with a married television producer. Schillings accused the newspaper of "falsely alleging that she had embarked upon a secret affair with a married man."

Schillings is also representing Timberlake in a lawsuit against the News of the World (search) tabloid over a story claiming he had cheated on Diaz.