(CNN) -- The arrest warrant used to detain filmmaker Roman Polanski in Switzerland was valid, the Swiss Justice Ministry said Tuesday, making clear it will fight the director's appeal against his detention over a 1977 sex case.
Director Roman Polanski fled the U.S. more than 30 years ago and was detained in Switzerland in September.
Polanski, 76, is challenging his detention on other grounds as well.
Swiss courts will have the final say on whether the warrant is valid and whether the director will be granted bail while he fights his extradition to the United States.
The Academy Award-winning director of "The Pianist" pleaded guilty in August 1977 to having unlawful sex with a 13-year-old girl. Prosecutors dropped other charges in exchange for his guilty plea.
But Polanski fled the the U.S. before sentencing after learning that the judge might not go along with the short jail term he expected to get from the plea agreement.
Los Angeles, California, authorities sought his arrest when they learned he would be traveling to Switzerland for a film festival last month.
Polanski remained free -- mostly living in France -- before his arrest in Switzerland on the 31-year-old warrant.
He agreed to pay his sexual assault victim $500,000 to settle a damage claim she filed against him nearly 12 years after the crime, according to court papers released Friday.
Polanski still owed the money -- plus another $100,000 interest -- three years after the 1993 settlement, according to the documents.
The victim sought money for damages suffered when Polanski had sex with her. She claimed Polanski plied her with alcohol and quaaludes during a photo shoot at the Hollywood Hills home of actor Jack Nicholson.
It's not clear if Polanski ever completed paying the woman, although court papers document efforts by her attorneys to garnish residuals and other payments owed to Polanski by the Screen Actors Guild, movie studios and other Hollywood businesses.
She long ago came forward and made her identity public -- saying she was disturbed by how the criminal case had been handled.
In January, Samantha Geimer, now 45, a married mother of three, called for the case to be tossed out.
In court papers, she said, "I am no longer a 13-year-old child. I have dealt with the difficulties of being a victim, have surmounted and surpassed them with one exception.
"Every time this case is brought to the attention of the court, great focus is made of me, my family, my mother and others. That attention is not pleasant to experience and is not worth maintaining over some irrelevant legal nicety, the continuation of the case."
Polanski's arrest has divided public opinion, even in Hollywood.
Some high-profile filmmakers such as Woody Allen, Martin Scorsese and Pedro Almodovar have called for his release.
But actress Kirstie Alley vehemently insisted on her Twitter page she does not celebrate or defend him.
"I can't believe that Hollywood has separated itself so completely from American morality," said Paul Petersen, a former child actor and president of A Minor Consideration, which advocates on behalf of young performers. "It is yet another case of Hollywood being out of sync with most of America."
Besides his win for "The Pianist," Polanski also was nominated for a best director Oscar for "Tess" and "Chinatown" and for best adapted screenplay for "Rosemary's Baby," which he also directed.
CNN's Carol Jordan, Eileen Hsieh and Alan Duke contributed to this report.