DS Smith looks set to close one of its South West sites with the loss of all 167 jobs.
The firm said a proposal had been made to shut the packaging plant in Launceston, Cornwall, and it was now entering consultation with the workforce.
DS Smith, which also has a sister plant in Devizes, Wiltshire, along with operations in Bristol, said the move was the result of a review of its UK packaging operations due to "tough trading conditions".
The group closed a plant in Plympton, Plymouth, last year.
The Launceston site first opened in 1968 under the Tillotson's name. It has since been the subject of a number of takeovers, including in January last year when it became part of a new business formed through the merger of International Paper and DS Smith, two of the world's leading producers of sustainable packaging and other products.
DS Smith said: "To improve efficiencies across our business and to ensure we respond to the evolving needs of our customers in what are tough trading conditions for the industry, we have undertaken a review of our UK packaging operations.
"As a result of this review, we can confirm a proposal has been made to close a site within our network. A consultation process with employees is ongoing, during which DS Smith (and International Paper) will not comment further."