Quiet drinks maker Britvic, which shares Unilever’s site, circulated plans to transfer production of Robinson and Fruit Shoot to east London, Leeds and Rugby.
That purposefulness affects 242 Britvic employees.
Colman’s has been based in Norfolk since Jeremiah Colman started his area in 1814.
Unilever confirmed it had begun a review of the Norwich plant.
Unilever, which has 113 wage-earners in Norwich, said: “Britvic and Unilever’s operations have been uniquely intertwined at the place for many years, relying on a shared infrastructure.
“Although no decisions compel ought to been made, we need to recognise that Britvic’s proposed withdrawal choice have serious implications for Unilever in Norwich,” the company said.
“The inspect will look in detail at the impact of Britvic’s proposed withdrawal from the position and will consider options for the most effective sourcing of the current Norwich yield range.
“One of those options will include the potential closure of our Norwich mill.”