The stars of Harry Potter have joined author JK Rowling to bid an emotional farewell to their fans as they turned out for the world premiere of the series finale.

Daniel Radcliffe, Emma Watson and Rupert Grint spent hours on the red carpet, which stretched from Trafalgar Square to Leicester Square, signing autographs at the screening of Harry Potter and the Deathly Hallows: Part 2 (2011).

Radcliffe , who plays the young wizard, received the biggest applause of the night when he told the crowd of 7,000 the films would be with them, "for the rest of their lives".

The evening ended with Rowling joining the cast and crew on a stage in the square where they addressed fans.

Watson, who wiped away tears, made a point of thanking her co-star Grint for making her laugh while he admitted making the films had been "the best part of my life".

Producer David Heyman said the three young stars were "still humble, still enthusiastic and still generous" even after the massive success they had enjoyed.

Rowling also wiped away tears before thanking the actors for "the amazing things they did for my favourite characters".

Turning to the fans, she said: "Thank you for queuing up for the books for all those years, for camping out in a wet Trafalgar Square ."

But she begged them to stop as they chanted "thank you" in return, saying "No, no, I'm already crying."

Radcliffe told the crowd: "Each and every person, not just here in this square but around the world who have watched these films for the last 10 years, they will always carry the films with them for the rest of their lives."

Fans had been arriving in London all week for the Harry Potter premiere with many of them camping in the square for days, some dressed as characters from the hit films.

Others waved placards reading "Potter 'til I die", "Harry Potter is over. See you in therapy" and "Thank you Jo for my childhood".

Other cast members who walked up the red carpet included Robbie Coltrane, Tom Felton and Julie Walters.

Jason Isaacs, who plays Lucius Malfoy, said he was not surprised by the reaction of the fans.

"The books are all about death and loss and mortality so they are very emotional and they make people emotional," he said.

"You find this wherever you go in the world. Harry Potter just seems to light up the world."

He said the finale was a "fitting climax" to the series.

"It's hard enough to come up with a last 20 minutes to a film but to come up with a last two hours to 10 years of films is astounding but I think they have pulled it off."

Source: Press Release