A number of roles at Nestle York may be axed as part of efficiency savings, the company has said.
Nestle has begun consultations with workers at the chocolate factory over the changes.
It comes amid reports that 66 staff are to be made redundant between the York site and its sister plant in Girvan, Scotland.
The York Press has seen a letter from Simon Barker, interim factory manager for York and Girvan, which says the company has seen sales affected by higher cocoa prices.
That means the company will be producing fewer KitKats this year and next. It means fewer people will be needed, Mr Barker said.
A Nestle spokesperson confirmed that consultations were underway, saying: “We are proposing some changes at our York factory to ensure manufacturing at our site is as efficient as possible.
“The proposal may involve a reduction in the number of positions required. As always, we are speaking to our employees about this proposal first and nothing will be confirmed until a consultation has been completed.”