More than 350 jobs are at risk after consumer goods giant Unilever and Robinsons squash owner Britvic announced plans that could see their shared manufacturing site in Norwich shut down.
Britvic announced on Tuesday morning it has tabled proposals to transfer production of Robinsons and Fruit Shoot from the Norwich factory to sites in east London, Leeds and Rugby as it looks to make "significant productivity and efficiency savings".
The company said 242 impacted employees will be offered a "comprehensive package of support", including redeployment opportunities at other sites and outplacement services to help find alternative employment.
Britvic is set to begin consultation with impacted employees and, under the plans, the site will close towards the end of 2019.
In a double blow for the city, Unilever has launched a review of its operations at the same site, putting a further 113 jobs at risk at its unit which produces Colman's Mustard.
The company said in a statement: "Following Britvic's announcement that it is proposing to close its manufacturing site in Norwich, Unilever will be launching a review of its production which is co-located at the site.
"Britvic and Unilever's operations have been uniquely intertwined at the site for many years, relying on a shared infrastructure. Although no decisions have been made, we need to recognise that Britvic's proposed withdrawal would have serious implications for Unilever in Norwich.
"One of those options will include the potential closure of our Norwich factory."
Colman's has had a presence in Norwich for more than 200 years and has been produced at the same factory since the 1860s.
Britvic boss Simon Litherland justified his firm's move by stating it presents "significant" productivity and efficiency savings in its manufacturing operations and delivers "environmental benefits".
In 2015 Britvic announced a three-year £240 million investment into its British manufacturing operations, a plan the firm says it is committed to despite the Norwich closure.
Mr Litherland added: "No decisions will be made prior to full and proper consultation with employees, and our focus is on ensuring we offer our colleagues ongoing support and assistance throughout this difficult time."
Union Unite reacted with fury to the news.
National officer Rhys McCarthy said: "The sad news that Britvic is closing its operations in Norwich also has an impact on Unilever workers who the share the same site.
"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. Anything else won't cut the mustard.
"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. Colman's is in the DNA of the city."