Hundreds of jobs at two Birds Eye factories could be at risk after the frozen food brand's owner said it was considering selling the business.
Grimsby's Birds Eye plant has closed after 50 years of production
Parent firm Unilever said on Friday it was reviewing its European frozen food business, which includes Birds Eye.
About 700 people work at the Lowestoft site in Suffolk producing frozen vegetables and 600 are based in Hull, East Yorkshire, making fish fingers.
In February, Unilever closed Birds Eye in Grimsby with the loss of 620 jobs.
Industry analysts say although the business is profitable it has suffered from low sales growth due to the poor image of frozen food as it competes against fresh foods.
Sales actually declined in Britain in the first six months of 2005, the company's figures show.
Unilever says an internal team is expected to report back on the review during the first quarter of 2006.
"It is genuinely an all-options, open review right through from one end of looking at possible acquisitions to the other end of total or partial sale and all things in between," a spokesman said.
Andy Worth, regional organiser for the GMB union, which has 400 members at the Hull plant, said: "We are extremely disturbed about this announcement.
"I know our members have been fearful for some time that they would close the plant.
"Rumours have gone round since they closed Grimsby that Hull would be next to be closed.
"We will be doing everything we can to make sure it is not."