The fourth, and darkest Harry Potter film so far premiered in London Sunday, extending a series that is already one of the most successful in movie history and still has three further episodes to run.

"Harry Potter and the Goblet of Fire" is based on the fourth instalment of author J.K. Rowling's seven-book series, in which young wizard Harry is tested to the limit in a magic tournament and meets his nemesis Lord Voldemort in a dramatic climax.

With death, danger and the first blossoming of teenage love at Hogwarts School of Witchcraft and Wizardry, the film has been ruled unsuitable for under-12s to watch unaccompanied by an adult, the first of the Potter films to get such a rating.

British director Mike Newell said he wanted to recreate the atmosphere he remembered when at school.

"I remember being terrified of some teachers at school who were violent," he said in a recent interview. "The teachers would clout us. But I also remember things being absolutely hysterically funny, because there was such anarchy."

He also defended his decision to make Goblet a darker film than the previous three. "There's a problem of credibility," he said. "If you think ... there is going to be the same sunlit, blush-toned childhood of film number one, there are a lot of questions that you will ask. You will tend not to believe that."

He described the budget for the two-and-a-half hour Goblet as "colossal", although the film's backers still made him argue for more money while making the film.

Industry estimates say Goblet cost somewhere between US$130 and US$170 million to make, but it could be a good investment considering that the first three films earned around US$2.5 billion at the box office.

Many of the stars of the fourth Potter film, which is in cinemas from November 18, appeared at Sunday's world premiere in central London, including Daniel Radcliffe who plays Harry and Ralph Fiennes who is the evil Lord Voldemort.

Source: China Daily