Roman Polanski went to Switzerland to receive a lifetime achievement award
The US has formally asked Switzerland to extradite film director Roman Polanski on sex charges, Swiss officials say.
Polanski has been wanted in the US since he fled the country in 1978, after pleading guilty to having unlawful sex with an under-age girl.
He was held in Zurich after travelling from France to collect an award at the city's film festival in September.
The director recently lost an appeal to be released on bail from a Swiss jail.
The Swiss justice ministry said in a statement that if it approved the US request, Polanski might appeal against the decision.
"The US Embassy in Bern submitted the formal extradition request... within the deadline of 40 days stipulated under the bilateral extradition treaty," the statement said.
Earlier this week Swiss authorities defended their action in informing the US that Polanski was travelling to Zurich.
The tip-off led to the 76-year-old's arrest.
Swiss officials said they were obliged to take Polanski into custody after learning that the decades-old warrant was still valid.
The director, who holds dual French and Polish citizenship, was originally charged with six offences, but pleaded guilty to unlawful sex with the 13-year-old girl following a plea bargain.
He has not set foot in the US since taking flight, and has settled in France.
In recent years, his lawyers have tried to have the case dismissed.