2 Sisters Food Group could pay compensation of more than £1m if an equal pay claim lodged by solicitors Leigh Day proves successful.

Female former employees of 2 Sisters’ chicken factory in Haughley Park, near Stowmarket, East Anglia, have lodged formal grievances with the food firm in the dispute.

The workers claim they were paid less than men for working in the same production line roles at the chicken factory, which closed down last November.

Claims management company Pay Justice, which is also acting on behalf of the workers, claimed some employees worked at the site for more than six years and could be potentially be entitled thousands of pounds in back pay, under the Equal Pay Act 1970. However, the workers’ average length of service is between three and four years.

The claim centres around a dispute that female staff were allegedly paid about £1.50/hour less than their male colleagues.

Pay Justice said in a statement: “2 Sisters is a massive company employing more than 20,000 people and with annual revenues of more than £3bn.”

The statement added: “We are keen to help any women who are currently working for 2 Sisters or who have in the past six years. If low-paid women are successful in making a claim, men doing the same work as the low-paid women will also be able to claim fair pay.”

Former 2 Sisters workers have filed a letter of grievance with the firm, claiming hundreds of thousands of pounds in back pay. And Leigh Day has applied for an employment tribunal hearing on behalf of 57 workers.

A spokeswoman for 2 Sisters said: “We can confirm that we have received a written grievance and we are currently reviewing its contents. It would be inappropriate to comment any further at this stage.”