ZURICH (Reuters) - The United States has formally asked Switzerland to extradite film director Roman Polanski, who fled sentencing in California on child sex charges in 1977, the Swiss Justice Department said on Friday.

The department said it would make a decision on extradition based on a hearing and on information provided by Polanski's lawyer.

In a statement, it said Polanski would be able to appeal against its decision to the Swiss Federal Criminal Court and, in the last instance, the Federal Supreme Court.

The 76-year-old Oscar-winning director, who holds dual French and Polish citizenship, was arrested at the request of the United States when he flew into Switzerland on September 26 to receive a lifetime achievement award at a film festival.

Polanski fled the United States 32 years ago, when he was due to be sentenced for having unlawful sex with a girl aged 13.

U.S. authorities had until the end of November to make a formal extradition request. U.S. judicial sources have said the extradition process is complex and could take years if Polanski challenges it.

A Swiss court rejected a bid by Polanski for release on bail earlier this week, saying the risk that he would flee was too high.

Polanski's lawyer Herve Temime declined to comment.

(Reporting by Sam Cage and Lisa Jucca; Editing by Kevin Liffey)