Original artwork used in the animated film The Snowman, worth a total of £20,000, has been stolen from London.
It is thought the Snowman cells may have been stolen to order
Thieves took at least 18 animation cells from the film's production headquarters which showed scenes of the film's two main characters - the snowman and the young boy James.
It is thought the cells were stolen to order by or for someone with extensive knowledge of animation.
The film's producer, John Coates, said: "These cells were some of the few remaining as most have been sold or perished in the 20 years since the film was made.
"They were due to be exhibited in Japan and Australia later this year and are of course irreplaceable.
"I am very saddened that these pieces will be lost to generations of people who love the film.
"These pictures have enormous personal and sentimental value to me."
Mr Coates said the animation has been placed on a register of stolen art and police have carried out forensic tests at the building.
The Snowman, which is an adaptation of Raymond Briggs's classic wordless children's book, has been broadcast in more than 100 countries and won numerous awards.