Britain's top court ruled Friday against supermarket giant Asda, whose mostly female store staff are seeking the same pay as its mainly male warehouse workers. The Supreme Court verdict was hailed by the GMB trade union as "massive" news that could spark compensation but Asda insisted the long-running legal battle was not over. More than 40,000 store workers brought equal pay claims against Asda after complaining that other staff in distribution depots were unfairly paid more. Law firm Leigh Day, representing store workers and enlisted by the GMB, argued that distribution depot staff get paid between £1.50 and £3.00 more per hour. Asda had claimed that store-based jobs were not comparable with warehouse work. Despite Friday's ruling, Asda warned that the fight is not over because it has not yet been ascertained whether the jobs are of equal value. "This ruling relates to one stage of a complex case that is likely to take several years to reach a conclusion," said an Asda spokesperson. "We are defending these claims because the pay in our stores and distribution centres is the same for colleagues doing the same jobs regardless of their gender. "Retail and distribution are very different sectors with their own distinct skill sets and pay rates." The legal battle began in 2016 when an employment tribunal decided that Asda store workers were entitled to compare themselves to distribution staff. That decision was upheld in 2019 by the Court of Appeal, but Asda then appealed to the Supreme Court. Late last year meanwhile, UK regulators launched a competition probe into the takeover of Asda by billionaire brothers who run petrol stations and food outlets. US retail giant Walmart had agreed in October to sell its UK division to billionaire brothers Mohsin and Zuber Issa and private equity firm TDR Capital for £6.8 billion ($8.7 billion, 7.4 billion euros). jbo-rfj/phz/lth