LONDON - THE stars of the sixth Harry Potter film walked up the red carpet in London on Tuesday to a rapturous welcome from thousands of fans who braved pouring rain for the world premiere of the new movie.

The pre-release buzz suggests 'Harry Potter and the Half-Blood Prince' will add a sizeable chunk to the US$4.5 billion (S$6.6 billion) in box office receipts already earned by the Potter movie franchise.

The film opens to the public in Europe on July 15, and in the United States and Japan two days later, after being moved back from its original release date of November 2008.

There was controversy just hours before the premiere, when London police charged Jamie Waylett, 19, who plays side-kick Vincent Crabbe to villain Draco Malfoy in the movies, with illegally growing cannabis plants.

One of the main actors, Rupert Grint, who plays Ron Weasley, attended the premiere after making a swift recovery from a mild case of H1N1 flu last week. 'Swine flu is nothing really, I found out. It's just like normal flu, it's just that you are in bed for a while,' he told AFP on the red carpet. 'Initially the words swine flu was kind of scary, but it was easy.'

Grint took his place alongside co-stars Daniel Radcliffe, who plays Harry, and Emma Watson, better known to fans as the nerdy Hermione Granger.

Radcliffe, 19, said he would miss the character when the Potter films come to an end in 2011, but also admitted he was looking forward to being able to pick and choose other projects. 'It's going to be very, very sad to finish these movies but at the same time it will be exciting, there's more stuff to move on to, so I'm not purely depressed about finishing them,' he said.

The trio have appeared in all six films so far, after being plucked from obscurity, and have spent nearly half their lives on the set or preparing for the big screen versions of the phenomenally popular JK Rowling books.

'The Half-Blood Prince' shows raging teenage hormones stalking the corridors of Hogwarts school and sets the scene for the looming final battle between Harry and his nemesis Lord Voldemort in the concluding films.

Director David Yates, who returns for his second Potter film and is helming the final two as well, said: 'For me this film marks a transition. The hormones are starting to fly.' -- AFP