Cinemagoers are well accustomed to being told a film is "the most eagerly awaited movie of the year" - but the tired claim seemed as if it might actually be justified yesterday as thousands of internet users rushed to catch a first glimpse of Harry Potter on celluloid in a trailer posted on the internet.

But the movie will not be coming to a cinema near you soon.

Audiences will have to wait until November to see it - making the trailer the most premature that Warner Brothers has ever released.

The studio plans to schedule the 110-second snippet for exhibition in cinemas, where it will serve less as an advertisement than as a temporary sedative for already hyperventilating fans.

A Warner spokeswoman said there had been "overwhelming interest" in the trailer, posted yesterday afternoon on the official website www.harrypotter.co.uk.

It follows the trainee wizard from his enrolment in Hogwarts School of Witchcraft and Wizardry to his discovery of the full extent of his magical powers, via special effects-laden scenes depicting the broomstick-piloting game of Quidditch.

Numerous enthusiasts, sounding suspiciously like adults, flocked to the site's discussion forums yesterday to analyse the brief clip in detail.

It is hard to draw many conclusions about the quality of the acting - 11-year-old Daniel Radcliffe, playing Harry, does not speak once.

However, the scenes drip with evidence of the £80m that has been poured into shooting of the film at the Leavesden studios in Hertfordshire.

Directed by Christopher Columbus, whose credits include Mrs Doubtfire and Stepmom, the film stars Alan Rickman, Maggie Smith, Robbie Coltrane and Ian Hart - plus a flock of computer-animated owls. These figure heavily in the online trailer.

The sneak preview should provide Warner with some respite from a spate of bad publicity surrounding the movie. It has left the studio risking looking as much of a representative of the forces of evil as Potter's diabolical nemesis Voldemort himself.

Within days of signing a $103m merchandising deal with Coca-Cola, Warner announced a partial cessation of hostilities in its bid to force several young fans operating websites to surrender internet domains which include the name Harry Potter.