A Birds Eye frozen food factory is to close later this year with the loss of hundreds of jobs and production moved to Germany, shocked workers were told today.
The GMB union said production was halted at the Hull plant this morning and workers were given the grim news.
According to the union, 600 jobs will be lost, although the company said the announcement involved around 490 redundancies.
The factory is in the constituency of Education Secretary Alan Johnson, according to the union, which said it would campaign "vigorously" against the decision.
The company has blamed excess capacity in its supply chain, particularly fish, for the decision and said its fish foods range will now be produced in Bremerhaven, Germany, and Lowestoft, Suffolk.
The union complained that when Unilever sold Birds Eye to venture capitalists Permira last year workers were given assurances about their jobs.
GMB official John Wilson accused Unilever of a "cynical" move in giving guarantees which have now been broken.
"Unfortunately, workers in Alan Johnson's constituency have now been hit by the curse of the venture capitalists."
The GMB repeated its complaint that venture capitalists had favourable tax arrangements on interest payments even though they "destroyed" the livelihoods of workers.
"We will mount a vigorous campaign to stop this work being moved to Germany", added Mr Wilson.
The union said the factory is set to close in September.
The site at Hull, which was established in 1967, is involved in the production of fish fingers and fish cakes, and pea processing. Birds Eye does not source any of its fish from the North Sea.
Staff will be given the opportunity to transfer from Hull to Lowestoft in Suffolk, where the company also has a factory.
Birds Eye Iglo chief executive Martin Glenn said: "We have inherited a business that has unsustainable over-capacity.
"The frozen food market is increasingly cost-driven. To be competitive, you require large-scale, highly-efficient production facilities.
"The future success of our fish category can be best served through the consolidation of our production facilities into our larger and more efficient sites in Bremerhaven and Lowestoft."
Birds Eye employs a total of 1,250 people in the UK.