Ashton Kutcher and Demi Moore. (Reuters file photo)

Ashton Kutcher is threatening to sue the editors of a U.S. tabloid for defamation following an article they published suggesting he had been cheating on his wife Demi Moore.

The actor took aim at a Star magazine report that his five-year marriage was "in danger of falling apart" following the "bombshell news" that the actor was "caught cheating with a sexy, young 20-something".

Kutcher took to Twitter.com earlier this week to address the scandal, writing, "STAR magazine - you don't get to stand behind 'freedom of the press' when you are writing fiction."

And now he's considering taking legal steps.

In a new Twitter.com post, Kutcher writes, "I think Star magazine calling me a 'cheater' qualifies as defamation of character. I hope my lawyer agrees."

Moore has yet to respond to the article, but she posted a look-at-me bikini photo on her own Twitter.com account on Wednesday, suggesting her husband has no need to stray.