Steven Spielberg's eagerly-awaited family blockbuster, "The BFG", is premiered at the Cannes film festival Saturday, with the Hollywood director on the Croisette himself to launch it.

The film is the first that the Hollywood legend -- who has had a string of children-orientated hits since "E.T." in 1982 -- has made directly for Disney.

And he has cast the rather diminutive -- in real life -- British actor Mark Rylance to play the friendly giant of Roald Dahl's classic children's book.

Every night the giant blows dreams into children's bedrooms and one night, passing an orphanage, he takes pity on a frightened young orphan inside called Sophie, saving her from the clutches of the horrid matron, Mrs Clonkers.

He brings her to live with him in the Giant Country, where the BFG is the sole vegetarian, with many of his neighbours preferring to eat children.

Dahl dedicated the book -- which became an instant bestseller it was published in 1982 -- to his daughter, Olivia, who had died of measles encephalitis two decades earlier.

The film was shot in Vancouver, Canada, with Rylance's face grafted onto the big-eared giant by New Zealand-based special effects company Weta Digital.

Dahl, a fighter pilot and spy who also scripted James Bond movies, wrote some of the most loved children's literature of the last century.

Several of his books, including "Charlie and the Chocolate Factory", "James and the Giant Peach" and "Matilda" have already been turned into major films.