Director Roman Polanski, who fled the United States in 1978 after pleading guilty to having sex with a 13-year-old girl in California, has been arrested in Switzerland.

In a statement, the Zurich Film Festival, where Polanski, 76, was due to receive a lifetime achievement award, said the Oscar-winning director was held on his arrival in Switzerland Saturday.

A U.S. warrant for his arrest was issued when Polanski left the country more than 30 years ago before his sentencing. Polanski, a French citizen, has never returned to the U.S. since then and has sought to have the case against him dismissed.

The Swiss Federal Department of Justice and Police, which confirmed Polanski's arrest on an outstanding American warrant, added that a decision to extradite him to the U.S. is subject to judicial procedure.

"Why now?," a friend of Polanski told PEOPLE on Sunday. "We don't understand. Roman has been to Switzerland before so we don't understand why he's been arrested this time."

Earlier this year, a California judge demanded that the director return to the U.S. in order to apply for dismissal – something Polanski has refused to do for fear of being arrested on arrival as a fugitive.

The Polish born filmmaker – whose films include Rosemary's Baby, Chinatown and 2002's The Pianist, for which he was named Best Director (Harrison Ford accepted on his behalf) – is married to French actress Emmanuelle Seigner and has two sons, Morgan and Elvis.

In 2005, he won a libel suit against Vanity Fair magazine over an article that accused him of propositioning a woman while on the way to the funeral of his murdered second wife, Sharon Tate, a victim of the 1969 Charles Manson killings.