Asda faces a claim to pay £100m ($121.9m) as back payments to thousands of female workers, employment solicitor Leigh Day has revealed. It comes after a class action related to the same was given the right to proceed by an employment tribunal in Manchester.

Day is representing 7,000 female shop floor workers who were or are working with the supermarket chain. They had complained of receiving between £1 and £3 less per hour than staff at Asda's distribution centres, which primarily consist of male workers.

The Walmart-owned retailer had argued that the difference in pay was not because of gender but because of the difference in location and the nature of work. However, these female workers argued that the work they do were of the same value as that done in the warehouses but they were getting paid lesser as Asda perceived their work as "women's work", worth less than men's work.

The tribunal ruled in favour of the women workers. It said that the jobs of these shopfloor women could be compared with jobs being done at the warehouses. While the case dates back to 2002, there are currently about 9,500 past and current workers who have joined this class action.

Lauren Lougheed, a lawyer representing the Asda women staff, said: "Asda tried to argue that because the shops and distribution centres were in different locations, with different pay arrangements, that Asda could pay the men what they like.

"However, the employment tribunal found that Asda, the employer of both men and women, could have made sure that there was equal pay between men and women if they wanted to, but chose not to."

Asda, however, argued that the employment tribunal ruling would not determine the eventual outcome of the case. "It relates to a technical preliminary issue of whether jobs in different parts of the business can be compared. The tribunal has yet to consider whether the jobs are of equal value in terms of their demands and if some jobs are, only then will the tribunal move on to consider the reasons for the differentials, including the existence of different market rates in different industry sectors," it was quoted as saying by Sky News.

The supermarket further argued that both men and women doing the same job in its retail stores were being paid the same, while both the sexes doing the same job in its distribution centres were also getting an equal pay. However, it said, "pay rates in stores differ from pay rates in distribution centres for legitimate reasons, including the different market rates for different jobs in different sectors."