Oscar-winning film director Roman Polanski has asked a Los Angeles court to dismiss a 30-year-old charge of unlawful sex with a minor, his lawyers said.

Polanski, 75, fled the United States in 1978 to avoid serving a prison sentence after entering a guilty plea on charges of having unlawful sex with a 13-year-old girl.

The film director's lawyers said they had new evidence, sparked by a documentary film earlier this year.

The film revealed "judicial and prosecutorial misconduct... so distorted the legal process that the interests of justice can only be served with complete dismissal of the case."

Polanski, who directed movie classics such as Rosemary's Baby and Chinatown, has French citizenship and cannot be extradited to the United States.

The French-Polish filmmaker has never returned to the United States despite winning a best director Oscar in 2003 for the World War Two movie The Pianist.

Polanski was originally charged with several counts, including rape by use of drugs. But in a plea deal, he pleaded guilty to unlawful sex with a minor.

He had already spent 42 days in a California prison for a psychiatric evaluation but then fled the United States before being sentenced.

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