Film-maker Roman Polanski is in detention awaiting possible extradition to the United States after travelling to Switzerland to receive an award.
The 76-year-old was detained in Zurich on Saturday under a 1978 warrant issued by the US.
Zurich police said they had carried out an international arrest order on behalf of Swiss justice authorities.
Justice Minister Eveline Widmer-Schlumpf said although Polanski had visited Switzerland in the past, his movements were not known beforehand. This time he was widely billed to be attending the Zurich Film Festival, which is holding a retrospective of his work.
The ministry said Polanski has been on a US wanted list since 2005 and was being held in temporary custody awaiting possible extradition.
"It is the rule of law and everybody is treated the same way, whether it is an ordinary citizen or a famous personality," said Widmer-Schlumpf. "It is purely a legal matter."
The US will now be given time to make a formal extradition request. Polanski can contest his detention and any extradition decision in the Swiss courts.
His lawyer Georges Kiejman told France Info radio on Sunday that he was going to try to lift the arrest warrant in Zurich, adding that the extradition convention between Switzerland and the US was "not very clear".
The US warrant is linked to Polanski's arrest in the late 1970s when he was charged with giving drugs and alcohol to a 13-year-old girl and having unlawful sex with her at a photo session at Jack Nicholson's Hollywood home.
Polanski maintained the girl was sexually experienced and had consented. He spent 42 days in prison undergoing psychiatric tests but fled the country before being sentenced.
He recently sought dismissal of his case on the grounds of misconduct by the now-deceased judge who had arranged a plea bargain and then reneged on it. Earlier this year the girl involved also filed to have the charges dismissed.
Polanski has been living in France for the past three decades and became a naturalised French citizen in 1976. In the past he has avoided countries that were likely to extradite him.
"Immense cultural scandal"
The French foreign ministry announced on Sunday that Bernard Kouchner had talked with his Swiss counterpart to express France's desire that Polanski's rights be respected and to ensure a favourable outcome.
Kouchner said the French authorities had also been in contact with Polanski's lawyer.
French Culture Minister Frédéric Mitterrand said he was "dumbfounded" to learn of the arrest of the French-Polish film-maker.
He said he greatly regretted that "a new ordeal should be inflicted on someone who has already known so many during his life" and added that President Nicolas Sarkozy was closely following the case and shared the hope that the situation would be resolved quickly.
Polanski had travelled to Switzerland to receive a lifetime achievement award from the Zurich Film Festival.
Organisers of the festival said they were dismayed and shocked at the news of the arrest.
The planned award presentation has been postponed but the retrospective is going ahead so that festival-goers can express their solidarity and admiration for him, the festival said.
The Swiss Filmmakers Association also criticised the arrest, saying it was "not only a grotesque farce of justice, but also an immense cultural scandal".
The justice minister responded by saying she understood their reaction but urged the association to consider the country's legal obligations.
swissinfo.ch and agencies
Born Raymond Polanski to Polish-Jewish parents on August 18, 1933, he spent the first three years of his life in Paris before the family returned to Poland.
He escaped from the Jewish ghetto in Krakow in 1940 as the Germans sealed it off. His mother later died in an Auschwitz gas chamber.
His first full-length feature film after graduation, Knife in the Water, won a number of awards.
In 1969, Polanski's pregnant wife, actress Sharon Tate, and six others were brutally murdered by followers of cult leader Charles Manson.
Polanski won a best director Oscar for The Pianist in 2003 as well as the Cannes film festival's coveted Palme d'Or the year before.