Mike Myers and Cameron Diaz play Shrek and Princess Fiona

Among those walking the green carpet in Los Angeles were Cameron Diaz and Justin Timberlake, who were dating while filming but have since split up.

Mike Myers, who plays the ogre Shrek, and Eddie Murphy, who plays Donkey, were also at the screening.

Shrek 2, which was released in 2004, became the highest-grossing animated film of all time.

Shrek the Third is one of a number of film sequels hitting cinemas this summer, with other anticipated releases including Pirates of the Caribbean: At World's End and the fifth Harry Potter film.

Spider-Man 3 has already broken the box office record for weekend takings, making $148m (�74m) in the US this weekend alone.

What's remained consistent is the sweetness: a sweet little message in the back, and what's in the front is very, very funny and inventive Eddie Murphy

Shrek producer Aron Warner said: "I think the success of Spider-Man only bodes well for us. For me, it means people are dying to go to the movies. And the more the better."

'Funny stuff'

The latest film sees Shrek and Princess Fiona, played by Diaz, living a fairytale life before Shrek is asked to take the throne following the death of the king.

But he is reluctant to take up his duty, while the evil Prince Charming, played by Rupert Everett, is eager to get his hands on the crown.

"I think they've incorporated all the characters more," said Eddie Murphy.

"The story isn't so much Shrek and Donkey and Fiona. It's everybody, everybody's got funny stuff to do.

"But what's remained consistent is the sweetness: a sweet little message in the back, and what's in the front is very, very funny and inventive.

Others stars of the film who attended the premiere included Antonio Banderas and Dame Julie Andrews.