Grampian Country Food has announced plans to close its Elmswell pork factory near Bury St Edmunds in Suffolk, with the loss of 380 jobs.
The plant processed pig meat into sausages, hams and other products but did not kill and pigs itself.
Farmers would therefore not be directly affected, as the meat would be put into other markets, a spokesman said.
Managing director Neil Hammond said he deeply regretted the decision, which will take effect in late June.
“As a result of continued manufacturing overcapacity within the pork sector combined with rising costs, which we have to date been unable to recoup, and our drive to improve the efficiencies within our business we regrettably have had to make this announcement.”