Polanski, 76, was arrested Sept. 26 in Zurich in connection with a 1977 child-sex case in Los Angeles.
The famous filmmaker, who lives in France but was in Switzerland to attend a film festival, has not traveled to the United States since he pleaded guilty in a Los Angeles court to having unlawful sex with a minor and then fled the country before he could be sentenced. He was accused of drugging and raping Samantha Geimer when she was 13.
Polanski's lawyers have alleged misconduct on the part of the Los Angeles criminal justice system at the time of the plea deal. They are fighting extradition from Switzerland to the United States.
"An arrest is a big operation and we needed to know if the warrant was still valid," the BBC quoted Swiss Justice Ministry representative Folco Galli as saying. "The Americans immediately confirmed that was the case."
Although the filmmaker has visited Switzerland for years, the British broadcaster said Polanski's scheduled appearance at the Zurich Film Festival was too high-profile for Swiss authorities to ignore.
Polanski's lawyer told France's Europe 1 Radio the director may end up going to the United States to answer the charges if he doesn't win his appeal to leave the prison in Zurich on bail.
"We could be heading towards an extradition if the Swiss justice system does not take into account arguments against it," the BBC quoted Georges Kiejman as saying. "If the procedure drags on, it is not impossible that Roman Polanski could choose to go and explain himself in the United States, where there are some arguments in his favor."