The woman says she was plied with champagne before the assault, that has "affected" her entire life. The alleged victim, who describes herself as a "naive 14-year-old virgin" at the time, says she had been to see the singer in concert with some friends after being given free tickets.
She told The Sun that she had never even "French-kissed" a boy at the time and that she couldn't understand the look on the star's face when he was "probably climaxing". Police are reportedly looking into the claims and she met with detectives last week.
It's alleged that the woman and her friends were invited to the singer's hotel the following day by a bodyguard who had spotted them giggling near to the stage.
The girls, 13 and 14 at the time, went along hoping to meet the pop star and get his autograph.
The woman, now in her 50s, says she was led to the balcony and offered a glass of champagne and took it to be "part of the crowd".
She said: "Before I knew it, it was like an immobility had set in there and then. He had me down on the bed in one fell swoop.
"His gown was off. I was wearing a jumpsuit. He zipped it down and what had started as affectionate and safe, almost, was suddenly becoming painful and forceful, not comfortable."
The woman says she left the room before going back because she had forgotten to get his autograph.
And when she went back, she says the star cupped her face and promised to stay in touch.
She added that she only realised later when she was showering that she was covered in bruises and that she'd been traumatised for years over the incident that she was too scared to tell her friends and family members about.
She said what happened left her obsessed with the singer and unable to have normal relationships with men.
An official probe was reportedly opened by police in 2014, but dropped six months later.
However, it was disclosed last month that a new prosecutor and investigating officer had been assigned to the case.