Attorney Herve Temime said there has been "no change in strategy," telling The Associated Press that Polanski will "continue to fight extradition" to the United States for having sex in 1977 with a 13-year-old girl.
Earlier Wednesday, fellow Polanski attorney Georges Kiejman told Europe 1 radio that Polanski could voluntarily return to face justice in Los Angeles.
Polanski has been pressing for his release since being arrested last month in Zurich. He suffered a major setback Tuesday when a Swiss criminal court rejected his offer of bail, saying his flight risk was too high.
Swiss officials tipped off the U.S. and set in motion the arrest of Polanski last month, according to documents obtained by the AP. On Wednesday, a top Swiss official defended the move.
Justice Ministry spokesman Folco Galli said the e-mails - obtained in Los Angeles by the AP under a U.S. public records request - showed that Swiss officials followed proper police procedure when a wanted individual is expected in Switzerland.
"An arrest is a big operation," Galli told the AP. "If we know a wanted individual is coming, we always ask if the arrest warrant is valid."
According to the e-mails, the Swiss ministry sent an urgent fax to the U.S. Office of International Affairs on Sept. 22 stating Polanski was traveling to Zurich. The director was to be feted at a film festival, and Swiss officials wanted to know if the U.S. would be submitting a request for his arrest as he was the subject of an international law enforcement "Red Notice."
"The Americans immediately confirmed that was the case," Galli said.
As a result, Switzerland was required by treaty to apprehend Polanski, he said.
Galli also addressed the nagging question of why authorities decided to go after Polanski now, even though the 76-year-old filmmaker has been a frequent visitor to Switzerland, where he owns an Alpine chalet. Unlike his previous visits, Polanski's appearance at this time was widely advertised, with the Zurich Film Festival promoting its upcoming tribute to the director of "Rosemary's Baby," "Chinatown" and "The Pianist" on its Web site.
Several Swiss politicians and commentators have argued that Switzerland may have cooperated too energetically, and that recent U.S.-Swiss troubles over wealthy American tax cheats and Swiss banks may have provided motivation for the arrest.
But Swiss authorities have adamantly rejected that suggestion.
"We have 20,000 warrant requests each year," Galli said, adding that this was the first time officials had precise details on the director's arrival and an official American request to arrest him.
After receiving the tip, U.S. federal officials alerted the Los Angeles district attorney's office, which immediately began drafting an arrest warrant. E-mails show U.S. authorities learned on Sept. 23 that Polanski was in Austria but officials doubted they could assemble an arrest warrant before Polanski had moved on to Switzerland.
Polanski was arrested three days later as he arrived in Zurich to receive a lifetime achievement award. He has been battling extradition ever since.
Polanski's offers of bail, house arrest and electronic monitoring failed to sway the Swiss tribunal. Even his chalet in the luxury resort of Gstaad was brushed aside as insufficient collateral to guard against Polanski fleeing the country, as the court noted that "the appellant has already once in 1978 eluded American criminal proceedings by traveling to Europe."
Kiejman, one of Polanski's French lawyers said Wednesday his client might just decide to give up fighting extradition.
"If the proceedings drag on, it's not completely impossible that Roman Polanski might decide to go explain himself in the United States, where there are arguments in his favor," Kiejman told Europe 1 radio.
A Sept. 25 e-mail from the Office of International Affairs to the Los Angeles district attorney's office shows U.S. authorities seemed confident that Polanski would not be released.
"Generally, Switzerland does not release fugitives sought for extradition," the e-mail states. "The default in Switzerland is that a fugitive will be detained until s/he is either extradited or determined by the Swiss Federal Supreme Court to be non-extraditable."
Laura Sweeney, a spokeswoman with the U.S. Department of Justice, said she could not comment on any of the events leading up to Switzerland's fax to the United States.
U.S. district attorney spokeswoman Sandi Gibbons said it was not unusual for her office to receive information on fugitives' whereabouts, but she declined to comment further.
Temime also refused to discuss what Swiss initiation of the arrest might mean for his client's attempts to be released.
But Peter Cosandey, a former Zurich prosecutor, said the revelation doesn't aid Polanski's case.
"This is normal procedure," Cosandey told the AP. "This also happened to me as prosecutor. The guy is traveling somewhere. You're asked, 'Are you looking for him. Do you still want to arrest him?"'
Dieter Jann, another ex-district attorney, agreed.
"This changes absolutely nothing," he said. "It's absolutely normal for countries to exchange tips on wanted people and to invite each other to take action. If it wasn't Polanski, everyone would think this is right."
Polanski was accused of plying a 13-year-old girl with champagne and part of a Quaalude pill during a modeling shoot in 1977 and raping her. He was initially indicted on six felony counts, including rape by use of drugs, child molesting and sodomy.
He pleaded guilty to the lesser charge of unlawful sexual intercourse and fled amid a legal dispute over the length of his sentence.
Polanski has until Oct. 29 to appeal the decision on his release. He also can continue attempts to persuade the Swiss Justice Ministry to release him. More court proceedings are expected after Washington files its formal extradition request, which it has until Nov. 25 to submit.
Legal experts said no path offered Polanski much hope for a speedy release from jail.
It is not clear how much time in jail Polanski faces now, either in Switzerland or in the United States. With appeals, the extradition process in Switzerland could take months. In the U.S., Polanski fled before sentencing was complete and is expected to face additional penalties for jumping bail.