Lawyers acting on behalf of Jude Law have contacted the News of the World newspaper over a story about the film star's private life.
Jude Law and Sadie Frost divorced in October 2003
The Sunday newspaper printed a story about Law and his former wife, Sadie Frost, on 30 January 2005.
Law's publicist put out a statement saying the claims were "completely untrue and highly defamatory" and warned other media not to repeat them.
A spokeswoman for the News of the World said they stood by their story "100%".
She also confirmed that the paper had received a letter from Law's libel lawyers, Carter-Ruck.
However, she refused to reveal whether they had responded.
Law, the star of Cold Mountain and Alfie, has increasingly been the subject of newspaper and magazine gossip columns since his split with Frost at the end of 2003.
Frost, 36, and Law, 31, married in 1997 and have three children together.
Law proposed to his Alfie co-star, 22-year-old Sienna Miller, on Christmas Day.