The Magic Roundabout is to be transformed from a cult TV series to a blockbuster feature film in a deal announced by a Bristol-based animator yesterday.

Zebedee, Dougal and Ermintrude the cow will make the transformation to the big screen in a big budget animation using the techniques pioneered by the makers of Toy Story.

Film-makers intend to cast familiar names to voice the characters, who became children's classics when they first appeared on television 35 years ago.

Initially the script will centre on the programme's colourful garden and its familiar red and yellow roundabout. All the characters, including Brian the snail and Dylan the hippie rabbit, will feature. But the story will later move outside the garden as the friends embark on a round-the-world adventure.

The film will be a co-production between the French company Films Action, which owns the rights for the Magic Roundabout, and Bolexbrothers, which is based in Bristol - home to the makers of Wallace and Gromit, Aardman Animations. It will be finished by the end of 2002, for release in 2003.

Andy Leighton, managing director of Bolexbrothers, said: "We intend to have a ball with this one. The story starts in the garden and then the characters go off on a big adventure around the world."

But he stressed that the film would remain true to the original characters. "It is our job to preserve the Magic Roundabout that we know and love. It also offers us a chance to develop the characters a bit more for all ages."

The original French version was created by Serge Danot, but it came to Britain without a script. Eric Thompson, father of the actor Emma Thompson, created his own story, and provided the voices. It was shown by the BBC from October 1965 to January 1977.