The second-largest biscuit supplier in the UK is to end production at one of its factories with the loss of up to 660 jobs.
The firm bakes some of the UK's best-known biscuit brands
Burton's Foods said the proposed cuts at its site in Moreton, Wirral, followed an "extensive" review of its business operations.
The company's chief executive said the job losses were "regrettable".
The union Unite said the decision would "devastate" the community and would be consulting with its members.
The plant, which makes Cadbury's chocolate biscuits, will continue to manufacture other products. It is propsed that 300 jobs will remain at Moreton.
The decision came after a five-month review of all the company's facilities, including plants at Blackpool, Edinburgh, Moreton and Llantarnam in south Wales.
Paul Kitchener, chief executive for Burton's Foods, blamed the "highly competitive UK biscuit market" for the planned job cuts.
He said that the potential job losses did not reflect on the commitment of the workers at the Moreton plant.
"However, we believe this is the best solution to embrace changes in the market and secure the long-term success of Burton's Foods and its remaining 2,400 employees," he said.
It is proposed that about 300 jobs will remain at Moreton.
Unite said the factory was the biggest employer on the Wirral after car giant Vauxhall.
Joint general secretary of Unite, Tony Woodley, said: "This is a company that has received a great deal of public support, and the closure, which will devastate the community, may reflect the recent takeover by venture capitalists.
"We are not going to just roll over and accept this.
"We will be urgently consulting with our members about a strategy to keep the factory open, and we will meet management on Monday to hear their rationale for this body-blow to Merseyside manufacturing."
The company's additional sites in Blackpool, Edinburgh, Llantarnam, its head office in St Albans and its distribution centre in Knowsley are not affected by the plans.
Burton's Foods, which was bought by a private equity firm earlier this year, makes Wagon Wheels, Jammie Dodgers and Maryland Cookies, as well as a range of Cadbury's chocolate biscuits under licence.