Dairy Crest may close its site at Totnes in Devon.
The company plans to consult unions and its 164 employees who work at the plant within 90 days.
The site is part of the non-returnable container (NRC) operations of Dairy Crest’s Dairies Division. Glass bottle and NRC milk production would be transferred to other sites.
The revelation was met with anger by the Transport & General Workers Union (T&GWU) section of Unite, the union.
Dave Springbett, regional industrial organiser for the T&GWU section of Unite said: "Dairy Crest is probably the biggest single employer in Totnes. We cannot let this plan go unchallenged.
"If this is a total closure where will the milk go and who will collect and transport it? This plan could have serious knock on effects."
The closure would incur exceptional cash costs of £3M and an exceptional non-cash asset write-down of £3M in the year ending March 2008, according to Dairy Crest.