Supermarket giant Tesco is reportedly facing Britain's largest ever equal pay claim with a bill potentially running to £4 billion.
Law firm Leigh Day has launched legal action against the company on behalf of nearly 100 shop assistants who claim they are paid up to £3 an hour less than their male warehouse workers, the Guardian reported.
The paper said that up to 200,000 staff could be affected by the claim, but Tesco said they work hard to ensure all staff are paid "fairly and equally".
It is reported that claims have been submitted to conciliation body Acas and it follows similar claims against Asda and Sainsbury's which are currently being dealt with by the employment tribunal process.
A Tesco spokesman said: "We are unable to comment on a claim that we have not received.
"Tesco has always been a place for people to get on in their career, regardless of their gender, background or education, and we work hard to make sure all our colleagues are paid fairly and equally for the jobs they do."