A US tabloid allegedly paid $150,000 to a former Playboy playmate for exclusive rights to her story about having an affair with Donald Trump but never published it, it has been claimed.

Karen McDougal, Playboy's 1998 playmate of the year, claims to have had an affair with Mr Trump in 2006 while he was married to his current wife, Melania. The claim has been strongly denied by Mr Trump, with his spokesman describing it as "totally untrue".

The Wall Street Journal claims that the National Enquirer bought the rights for the story. American Media Inc, which owns the National Enquirer, confirmed that the payment had been made but said it was for a column.

It said that it was paying Ms McDougal for two years' worth of fitness columns and magazine columns as well as "exclusive life rights to any relationship she has had with a then married man.

"AMI has not paid people to kill damaging stories about Mr Trump," the magazine's owner said in a statement.