Nestle has announced plans to cut almost 600 jobs and close a confectionery factory in Newcastle.
The world's largest food company wants to close its site in Fawdon by the end of 2023 and focus production on factories in York and Halifax.
It said 573 jobs would be "put at risk" by the changes.
The GMB and Unite unions said 475 jobs would be lost at Fawdon, where Fruit Pastilles are made, and 98 at the York factory, which produces KitKats.
Nestle said it would invest £20m into the York facility to "increase production of KitKat in the city where the brand was first created in 1935".
About £9.2m would be spent at Halifax to "take on the largest portion of Fawdon's current production", a company spokeswoman said.
The Fawdon factory opened in 1958 and currently produces 15 brands including Fruit Pastilles, Matchmakers and Rolos.
"We do not underestimate the impact that the closure of Fawdon factory would have on the local area and, as part of the consultation, we want to work with the local community to find ways that we can support the area and our employees if these proposals were to go ahead," Nestle said.
"We believe that the business case behind these proposed changes is compelling and, ultimately, the best way to keep our business competitive in the long term."
Ross Murdoch, GMB National Officer, said: "To ruin hundreds of lives in a ruthless pursuit of profits, to the very workers who've kept the company going during a global pandemic, is sickening.
"Nestle is the largest food producer in the world, with astronomical profits. It can afford to treat workers right.
"It's corporate greed at its worst - GMB and Unite will fight for every job."
Joe Clarke, Unite National Officer for the food and drink industry, said: "The news about Nestle's plans for its respective sites in Newcastle and York is a cruel body blow to the dedicated workforces, their families and, more widely, the regional economies.
"We will be asking for an urgent meeting with the management to ascertain the business rationale for these decisions from a multi-national company which is highly profitable.
"The fact these announcements have come during a global pandemic is particularly bitter and heartless."
