Around 100 unionised workers will take part in 24-hour strikes over 29 May, 1 June, 5 June, and 9 June, which organising union Unite claims will cause “significant disruption” to Amcor’s operations, including customers such as Walkers and Kellogg’s, a claim contested by Amcor.

Workers voted overwhelmingly for action following the breakdown of pay negotiations, with an 85% ballot turnout giving 93% in favour of withdrawing their labour.

The workers perform a number of roles at the factory, including printing, extrusion and lamination of packaging.

Unite representatives explained that workers had been offered 6%, a real-terms pay cut given that workers had seen inflation at 9.1% on the retail price index (RPI) when the pay rise was due to be implemented in October 2023.

The workers’ pay rise for 2022 was also 6% below the real level of inflation at the time, according to Unite.

Sharon Graham, the union’s general secretary, said: “Amcor cannot expect its workers to swallow a real terms pay cut for the second year in a row. It can fully afford to put forward a fair pay offer. Unite does not tolerate attacks on our members’ jobs, pay or conditions and the Amcor Workington workforce have their union’s total support.”

Amcor Packaging's UK operations had sales of £129m in 2023.

Unite regional officer Ryan Armstrong said: “Kellogg’s and Walkers will not be happy, they are facing packaging delays that could result in shortages for consumers.

“This is entirely the fault of Amcor for refusing to put forward a fair deal. Strike action can still be avoided but that requires an offer being made that our members can accept.”

The Cumbrian facility was last hit by strikes in 2022, when Sun Chemical employees at an in-plant ink facility took strike action over an “insulting” 3% pay offer alongside Sun Chemical’s other UK workers.

In a statement to Printweek, Amcor said that it respected the right of its employees' voices to be expressed and heard, and that meetings with union representatives were ongoing.

It said: "The aim of the company is to reach an agreement that benefits our employees whilst maintaining the competitiveness of the site. During this period, we will continue to focus on safe working practices for our employees, and providing uninterrupted service to our customers.

"We do not expect the strike to have a negative impact on our customers' supply of packaging."