The paper and packaging group has announced a minimum 45-day consultation with employee representatives concerning a proposed plan to close all manufacturing operations at its Deeside Industrial Park site in Flintshire and its Nelson, Lancashire site by the second half of 2020.

Union Unite said the workforce has been told that the work from the two sites, which produce a wide variety of flexible packaging, bags and pouches, will now be transferred to other locations within Mondi’s global business.

Mondi closed its Scunthorpe flexible packaging plant in 2018.

A Mondi spokesperson said: “The business has implemented various strategic initiatives over the past two years to streamline operations and enhance the cost-competitiveness of both sites, however due to the change in demand for the niche products produced at these sites, Mondi sees no alternative than to start a consultation process on the potential closure.

“Mondi understands this is a particularly challenging time for employees and their families and is committed to treating people fairly throughout the process. Employees will be given support during the consultation and implementation of the ultimately agreed proposal, and Mondi will follow all legal procedures in accordance with UK labour law.

“Mondi remains fully committed to flexible plastics packaging and will continue to serve its UK customers from its wide network of production facilities across Europe.”

A Mondi spokesperson told Printweek it already serves around 100 UK-based customers from its production sites in Poland, Germany, Hungary and Austria and that its service levels "will remain unchanged".

While the factory closures would put an end to Mondi's manufacturing in the UK, the business said it remains open to consider future opportunities "as and when they arise" in support of its strategic objectives.

Nearly 170 of the affected jobs are at the Deeside site in North Wales and Unite Wales regional secretary Peter Hughes said its members who work at the site are “in complete shock following the announcement”.

“This is a betrayal of a loyal workforce, who only two years ago rescued the site from administration.

“Unite expects answers from Mondi and a full explanation as to how they have come to this disgraceful decision. We will be subjecting Mondi to rigorous scrutiny and doing everything within our power to reverse this announcement.”

He added: “If this decision is upheld it will have a devastating effect on the economy of North Wales and be yet another hammer blow to our manufacturing base in Wales.”

Last week Mondi said its chief executive Peter Oswald would step down from the business at the end of March. It did not give a reason for the departure but said it was beginning the process of searching for a successor.