The Swiss authorities have admitted they tipped off their US counterparts that director Roman Polanski was travelling to Zurich.The move triggered his arrest last month over a charge dating back to 1977 of unlawful sex with a minor. The US is seeking his extradition. 76-year-old Polanski was taken into custody when he travelled from France to Zurich to collect an award at the city’s film festival. A Swiss Federal Office spokesman justified contacting the US. “ We wanted to avoid arresting someone unnecessarily. The American authorities confirmed to us in two days that they were interested in the arrest of Roman Polanski in order to proceed with his extradition.” The Swiss admission contradicts earlier claims that Polanski’s detention in a Swiss prison was initiated purely by the US. It also raises questions why the director’s file was flagged up now since he has been a regular visitor for years. Earlier a Swiss court rejected his bid for release on bail on the grounds he might flee the country. The Oscar winning director is said to be considering an appeal.