Ministry spokesman, Folco Galli, told The Associated Press that the risk was too great for the government to accept bail or other security measures in exchange for the release of the filmmaker who is wanted by US authorities for having sex in 1977 with a 13-year-old girl. 

"We continue to be of the opinion that there is a high risk of flight," said Galli. 

Polanski was apprehended September 26 as he arrived in Zurich to receive an award from a film festival. 

Authorities in Los Angeles consider him a convicted felon and a fugitive, and Switzerland claims there has been an international warrant out on him since 2005. 

Galli said the Justice Ministry has submitted a letter to the tribunal explaining why it opposes release even on bail.

Legal experts say Polanski stands a minimal chance of a speedy release, even if his lawyers have suggested he be held under house arrest in his chalet in the luxury resort of Gstaad.

"In practice, I don't remember any case where a fugitive has been released on bail while awaiting extradition to a foreign country," said former Zurich prosecutor Peter Cosandey, adding that Polanski's ownership of an Alpine chalet doesn't aid his case greatly.

Dieter Jann, another ex Zurich prosecutor, has said extradition would be hard to fight, and he thought Switzerland had followed procedures correctly.

In Paris, Polanski's lawyers took note of the decision and said they would focus on convincing the court to free Polanski.

Galli confirmed that Washington has yet to file a formal request seeking extradition. But said the US probably wouldn't need its entire 60-day period to submit all documents. 

"I assume this is a priority case in the United States," he added.