A Turkish film that tells the story of a 6-year-old boy who stops speaking when his father disappears, Bal, or "Honey", has won the top honour at this year's Berlin film festival.

Roman Polanski won the award for best director on Saturday for The Ghost Writer. The film's producers accepted the award on behalf of Polanski, who is under house arrest in Switzerland.

Producer Alain Sarde said Polanski told him he would not have attended the festival had he been free because the last time he travelled to accept an award he "landed in jail".