She told the British tabloid: "It was so easy to get into the palace and it troubled me because I could have been anyone.
"I didn't know Andrew and never met anyone from the royal household. Nobody knew me. I wasn't spoken to by a Royal Protection officer or asked any questions at all.
"Nobody checked my bag when I arrived or when I left. I certainly expected more stringent security checks."
Monique has showed off a cheque for £75 ($AU140) she says she was given to treat Andrew by his then-Assistant Private Secretary Charlotte Manley for the service.
She also massaged Ghislaine at her Belgravia home on two occasions - the same home the alleged picture of Andrew and Virginia Roberts was taken. She claims Jeffrey Epstein, who died by suicide in August, was present at the time.
The news comes after Prince Andrew's car crash interview with BBC Newsnight, which caused him to step down from his princely duties.
Andrew's interview featured a number of eyebrow-raising admissions, but none more so than his excuse to his whereabouts on the day that Virginia Roberts claimed that Epstein trafficked her for sex with him in London.
The Duke of York claimed he could not have had sex with a teenage girl in the London home of his "good friend" British socialite Ghislaine because he was at home after attending a children’s party at Pizza Express in Woking, England.
Andrew, dad to Beatrice, 31, and Eugenie, 29, with ex-wife Sarah Ferguson, said: “That couldn’t have happened because the date being suggested — the 10th of March — I was at home with the children.
“I’d taken Beatrice to a Pizza Express in Woking for a party at about 4 or 5 in the afternoon and then because the Duchess was away, we have a simple rule in the family that when one is away the other is there.”
He was asked why he could remember going for something so mundane as a pizza 18 years on, and he added: "Because going to Pizza Express in Woking is a very unusual thing for me to do. I’ve never been . . . I’ve only been to Woking a couple of times and I remember it weirdly distinctly. As soon as somebody reminded me of it, I went, 'Oh yes I remember that.'"
Virginia has claimed that she was forced to have sex with Andrew by Epstein.