LONDON (AP) — British supermarket chain Tesco is facing legal claims that it is paying women less than men for work of equal value, in a case that lawyers estimate could ultimately cost it as much as 4 billion pounds ($5.6 billion) in compensation payments.

Law firm Leigh Day says it has begun filing claims with the employee conciliation service Acas on behalf of 100 women, but the case could eventually apply to more than 200,000 Tesco workers.

The lawyers argue that in-store employees, who are largely women, are paid far less than those in the male-dominated distribution centers, even though their work is of equal value to the company.

Tesco says it works hard "to make sure all our colleagues are paid fairly and equally for the jobs they do."