Mirren wins best actress for 'The Queen'

Dame Helen as Elizabeth II takes top Venice prize and screenwriter thanks Tony Blair for 'political disintegration'

Dame Helen Mirren was last night named best actress at the Venice Film Festival for her performance in Stephen Frears's film The Queen, depicting the days following the death of Diana, Princess of Wales. The win is certain to boost Dame Helen's chances of an Oscar.

But The Queen failed to pick up the Golden Lion for best film - the honour went instead to Chinese entry Sanxia Haoren (Still Life). The best director prize was awarded to veteran French film-maker Alain Resnais for the film Private Fears in Public Places, while Ben Affleck was the surprise winner of the best actor prize for his role in Hollywoodland.

The Queen won one further award: best screenplay, for Peter Morgan. Collecting his prize, Morgan quipped: "Thank you, Tony Blair, for timing your political disintegration with the release of our film."

Dame Helen, 61, dressed in an elegant blue gown and Bulgari diamonds, was introduced on stage as "Her Majesty Helen Mirren". She gave the audience a joke curtsy as she accepted her award. "It's always terrifying to send your movie out for its first little toddling steps," she said. "It's an incredible honour to have this film take its first steps here at the Venice Film Festival."

The actress insisted her performance was just a small component of the film. She described director Frears and writer Morgan as the "father and mother" of the film, adding that she was "just a part of the DNA".

In other awards Spike Lee's devastating film about hurricane Katrina, When the Levees Broke: A Requiem In Four Acts, won the documentary prize. Children of Men, Alfonso Cuaron's film set in a dystopian London and starring Clive Owen, won the technical prize for its director of photography, Emmanuel Lubezki. There was a British win in the best European short film category. The prize went to Daniel Elliott for his 21-minute short The Making of Parts.

The top film award to Chinese director Jia Zhang-ke was a surprise entry late in the festival, and trumped such candidates as The Queen, and Emilio Estevez's Bobby, about a dozen or so characters at the Ambassador Hotel in Los Angeles the night Robert Kennedy was shot in 1968.

Still Life was shot in the old village of Fengjie, which has been destroyed by the building of the Three Gorges dam, and tells of people who go back there. More than 1.13m Chinese have been relocated to make way for the dam, many of them complaining of bleak prospects in their new homes above the waterline or in other parts of China.

"We were told there would be a surprise film at the end of this festival, and we didn't have a lot of discussion," French actress Catherine Deneuve, who headed the jury that awarded the top prize, told reporters.

"We were very touched," she added. "We know it's a very special film."