LOS ANGELES  In a surprising move arranged by prosecutors in Los Angeles and Washington, the authorities in Switzerland arrested the film director Roman Polanski late Saturday as he arrived at the Zurich airport, paving the way for his possible extradition to the United States in connection with a 32-year-old sex case.

Mr. Polanski, 76, a French citizen, was detained as he arrived to receive an award at the Zurich Film Festival. Although he is expected to oppose extradition, the arrest raised a strong possibility that Mr. Polanski would be returned to the United States to face sentencing under his conviction for having had sex with a 13-year-old girl in 1977.

The arrest came as a shock to Mr. Polanski and those who have worked closely with him both on movies and in a continuing attempt to lift the outstanding arrest warrant against him. He had just finished shooting a film in Germany and often travels to Switzerland, where he maintains a home.

In Paris the French culture minister, Frédéric Mitterrand, said in a statement that he was astonished by the arrest. In a separate statement the French foreign minister, Bernard Kouchner, said he had spoken with his Swiss counterpart and communicated “the desire of the French authorities that the rights of Mr. Polanski be fully respected and that this affair rapidly find a favorable resolution.”