The York plant makes up to 7 million Kit Kat bars a day and employs 1,800 people.
The firm said its other site in Halifax, which employs 500 people rising to 800 at peak production, is progressing well with the implementation of a new line to manufacture Peanut Butter Cups for the US market. The line will open later this year with the creation of a number of new jobs.
Nestle’s said first quarter sales were boosted by an early Easter, but growth was dented by currency changes.
The consumer goods giant said total sales rose 0.5 per cent to £14.6bn following stronger sales in western Europe, but it had a slow start to the year in America.
Organic sales growth was much higher at 4.4 per cent, while acquisitions added a further 0.6 per cent, but the increase was pegged back by a 4.5 per cent hit from currency movements.
Nestle’s Europe, Middle East and North Africa (EMENA) region was worst affected, with a 12.7 per cent impact from foreign exchange.
It comes after a surprise move in January to lift a cap which had fixed the Swiss franc’s value at no more than 1.20 euros
Removal of the peg sent the franc soaring against the single currency.
The company said it had a tough start to the year in North America, with frozen meals remaining “challenged”, especially its Lean Cuisine brand.
In the EMENA area including western Europe, cat food brand Felix and coffee Nescafe Dolce Gusto grew well, while confectionery was helped by the early timing of Easter. The group said most markets in western Europe did well though Switzerland and Greece had a slower start to the year.
Bottle water brands Perrier and S. Pellegrino showed good growth.