Tito Beltran, 42, is accused of raping the woman at a hotel in Nötesjö in Skåne following a performance at a concert in the area. A number of other well-known Swedish performers were staying at the hotel, and have been interviewed in the police investigation.
Chilean-born Beltran goes on trial next week at Ystad District Court. Speaking from his remand centre, Beltran insisted to tabloid Aftonbladet that he had only given the nanny, who worked for actress Maria Lundqvist, a back massage.
"In all my life I have never raped anyone and never hit a woman," he told the paper. Beltran said that the young woman came to his room, eventually stripping down to her underwear. He said they slept side by side, but insisted that it was "very innocent."
Following the alleged attack, Maria Lundqvist encouraged the nanny to report Beltran to the police. She is now among those set to testify against the tenor. Among other stars due to give evidence in court are musician Robert Wells, Eurovision star Carola Häggkvist and singer Lill Lindfors.
In a separate matter, Beltran was cleared last year of charges of sexually abusing a girl, who is now aged 13, between 2000 and 2002. The prosecutor has appealed Beltran's acquittal to Gothenburg District Court.
Beltran has become a well-known tenor in opera houses around the world, performing regularly at London's Royal Opera and the San Francisco Opera. He has also made regular appearances on Swedish television.