Actor Ashton Kutcher is reportedly threatening to sue the editors of a US 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'.

The actor is angry over the infidelity reports and has threatened to sue the magazine, reports imdb.com.

'Star magazine - you don't get to stand behind 'freedom of the press' when you are writing fiction. I think Star magazine calling me a 'cheater' qualifies as defamation of character. I hope my lawyer agrees,' Kutcher posted on his Twitter page.