Swiss police have detained the film director Roman Polanski on an arrest warrant issued in the United States 31 years ago. Mr. Polanski was in Zurich attending a film festival where he was due to receive a life time achievement award today. He was detained by Zurich police on arrival in Switzerland last night. A police spokesman said the action was taken under instuctions from the Swiss Federal Justice and Police department. The arrest warrant was issued after Mr. Polanski fled the US in 1978 after admitting sexual relations with a 13 year old girl.<br/><br/>