Wallace and Gromit creators Aardman Animations and US studio Dreamworks have ended a five-film deal early after two movies reportedly underperformed.
Losses were reported for their last two films, Flushed Away and Wallace & Gromit: The Curse of the Were-Rabbit.
The companies have released three films together, also including Chicken Run.
Dreamworks said the firms now had "different business goals", while Bristol-based Aardman Animations said their "ambitions have moved apart".
A fourth planned film, Crood Awakening, co-written by John Cleese, will now be a Dreamworks production with no Aardman involvement.
Aardman spokesman Arthur Sheriff said the separation was a result of Dreamworks' move to focus on computer animation.
The UK animators wanted to continue making their distinctive "claymations", he said.
"We always knew that America would be a hard task for us - we're a very English company," he added.
"We embrace the international market but we think part of our strength is our English sense of humour and we want to continue with that."
Aardman owners Peter Lord and David Sproxton said they had enjoyed a "hugely successful and creative relationship" with Dreamworks.
"But both companies are aware that our ambitions have moved apart, and it feels like the right time to move on," they said.
"Aardman has an ambitious slate of feature film projects in development and we will announce our future production and distribution plans shortly."
Dreamworks 'fan'
Dreamworks chief executive Jeffrey Katzenberg said the studio would make two computer-animated films a year and had those planned up to 2010.
"While I will always be a fan and an admirer of Aardman's work, our different business goals no longer support each other," he said.
The companies struck a five-film distribution deal in 1999.
The first feature film starring Aardman's most-famous creations, inventor Wallace and his dog Gromit, won last year's Oscar for best animated feature.
A US version of the studio's Creature Comforts TV series is to be broadcast later this year.
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