Karen McDougal claims the nine-month affair with the future US president took place shortly after Mr Trump’s wife Melania gave birth to the couple’s son Barron and a magazine bought her story in order to bury it. Mr Trump denies any affair.
The White House said: “This is an old story that is just more fake news. The president says he never had a relationship with McDougal.”
Ms McDougal, 46, a former Playmate of the Year, said she met Mr Trump at a Playboy Mansion party in 2006 and he “immediately took a liking” to her. The New Yorker magazine is understood to have obtained a hand-written account of the affair, which she confirms was in her own handwriting.
The eight-page document said Ms McDougal visited Mr Trump at a private bungalow in the Beverly Hills Hotel and he offered her cash after their first sexual encounter.
“We talked for a couple hours – then, it was ‘ON’! We got naked + had sex,” she wrote.
After Mr Trump allegedly offered her money she said: “I looked at him (+ felt sad) + said, ‘No thanks – I’m not ‘that girl’. I slept w/you because I like you – NOT for money’ – He told me ‘you are special’.’’
Ms McDougal said she ended the affair in 2007 over racially-charged comments she claimed he made about black men and crude remarks about a friend.
She was persuaded to sell her account for $150,000 (£107,000) but it was never published, in what she said was an attempt to hush up the story.
The allegations come just a month after Mr Trump was forced to deny an alleged affair with porn actress Stormy Daniels, who claimed she had a fling with him soon after Barron’s birth.