Britvic has announced plans to close its Norwich site and transfer production to sites in east London, Leeds and Rugby.
The proposals will mean the loss of 242 jobs as production of Robinsons and Fruit Shoots transfers to the alternative sites. Unilever, which shares the site, said that the closure of would also impact its employees.
Britvic chief executive Simon Litherland said: "This is not a proposal that we make lightly and we know this is upsetting news for our colleagues. We are very grateful for the hard work and dedication of our employees at our Norwich factory and today's announcement is in no way a reflection on their performance or commitment.
"However, the changes we are proposing today present significant productivity and efficiency savings in our manufacturing operations, deliver environmental benefits and, coupled with our ongoing investment programme in our GB manufacturing operations, ensure that we have the flexibility and capability we need to respond to changing consumer trends faster and more efficiently. No decisions will be made prior to full and proper consultation with employees and our focus is on ensuring we offer our colleagues on-going support and assistance throughout this difficult time."
Responding to the news Ivan Mercer, GMB regional organiser, said: "GMB have over 150 members employed at the Norwich site. This is not just a blow for Norwich but Norfolk manufacturing in general as employees live across the whole of the county.
"GMB will do everything we can to mitigate the effects of closure on our members and will seek to meet with the company at the earliest opportunity to discuss this proposal further."
The site in Norwich is co-owned by Britvic and Unilever, where Unilever's iconic Colman's Mustard brand has been manufactured since the 1860s.
Representing the Unilever engineering employees, Rhys McCarthy, union officer for Unite, added: "The sad news that Britvic is closing its operations in Norwich also has an impact on Unilever workers who the share the same site.
"This is very painful news for our members and their families at Britvic and we will be giving the maximum support to our members at what is a very difficult time in the days and weeks ahead.
"Unilever has today announced a review of the whole site to be concluded by the end of November. Everything is up for review including expanding its operations, selling part of the site and, more worryingly, closure.
McCarthy added: "Unite will not only be seeking assurances, but applying pressure with the support of the local community, that the production and the much-needed jobs that are vital for the Norwich economy remain.
"The whole of Norfolk needs to come together to fight for the future of Colman's Mustard that is so identified with the city of Norwich and part of the DNA of the city."
The proposals have been approved by the Britvic Board for consultation with impacted employees and, subject to full and proper consultation, it is proposed that the site will close towards the end of 2019.
Britvic has confirmed that there are 242 employees on site affected by this decision and that every impacted employee will be offered a comprehensive package of support, including redeployment opportunities at other sites and outplacement services to help find alternative employment.
The Unilever part of the site has about 60 workers belonging to the GMB union, with Unite representing 10 engineering workers.
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