Harry Potter stars at film premiere | Warwick Movies | Movie Reviews and Cinemas in Warwick

Rupert Grint, Daniel Radcliffe and Emma Watson at the premiere of Harry Potter and the Half-Blood Prince.

AAP

THE stars of the sixth Harry Potter film have walked up the red carpet in London to a rapturous welcome from thousands of fans, after one of the actors shook off a mild case of swine flu.

The pre-release buzz suggests Harry Potter and the Half-Blood Prince will add a sizeable chunk to the $US4.5 billion ($A5.65 billion) in box office receipts already earned by the Potter movie franchise.

One of the main actors, Rupert Grint, who plays Ron Weasley, was attending the premiere on Tuesday after making a swift recovery from a mild case of swine flu last week.

"It was quite scary when I first found out I had swine flu. I thought 'Am I going to die?' But it was just like any other flu really," he told journalists on Monday.

Grint will take his place alongside co-stars Daniel Radcliffe, who is Harry, and Emma Watson, better known to fans as Hermione Granger.

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.

Fans gathered in London's Leicester Square hours before the premiere and many said they were enjoying growing up with the characters.

After the red-carpet spectacular, the actors will continue filming the final two movies in the series - the concluding book Harry Potter and the Deathly Hallows was thought too plot-heavy for just one film.

Radcliffe, 19, says he will miss the character when the Potter films come to an end in 2011.

"I've had a fantastic time with Harry Potter, I've loved it. I'll be very sad to leave."

He admitted though that he was looking forward to being able to pick and choose other projects.

"A script will come in and I will not have to say, 'I am busy for the next four years'," he said on Monday.

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.

But Watson, who has grown from a shy 10-year-old in the first film to an elegant 19-year-old who models for fashion house Burberry, quashed any thoughts of real romance between the stars.

"We have grown up together from the age of 10 to 19 or 20, and we are just like siblings. There is nothing between the three of us."

The actors are expected to wear white ribbons on their wrists at the premiere as a mark of respect for murdered cast member Rob Knox, who was stabbed to death outside a bar last year just days after completing the film.

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