More than 44,000 Asda workers have won the latest leg of their equal pay claim with bosses through a Supreme Court ruling, paving the way for a legal battle that could last years.

The UK’s highest court backed a Court of Appeal judgment that store staff are entitled to compare themselves to distribution staff for equal pay purposes.

The store workers, mostly women and members of the GMB union, have brought equal pay claims on the grounds that those in the supermarket chain’s warehouses, mostly men, unfairly get more money.

Law firm Leigh Day, which is representing them, says distribution depot workers get between £1.50 and £3 an hour more and that the issue has far wider implications across the economy.

Lauren Lougheed, a partner at Leigh Day, said of the ruling: “We are delighted that our clients have cleared such a big hurdle in their fight for equal pay.

“Already an employment tribunal, the Employment Appeal Tribunal and the Court of Appeal ruled that these roles can be compared, and now the Supreme Court has come to the same conclusion.

“It’s our hope that Asda will now stop dragging its heels and pay their staff what they are worth.”

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The case, which stems from a 2016 employment tribunal decision on pay going back to 2002, pre-dates the £6.8bn sale of Asda by US grocery giant Walmart to a consortium earlier this year.

Bosses have long argued that store jobs are not comparable to distribution centre roles.

An Asda spokesman said of Friday’s judgment: “This ruling relates to one stage of a complex case that is likely to take several years to reach a conclusion.

“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.

“Asda has always paid colleagues the market rate in these sectors and we remain confident in our case.”

Lawyers for the staff say the next stage of their fight will involve a further employment tribunal case to seek whether specific store and distribution jobs are of “equal value”.

It could then, potentially, ask a tribunal to consider whether there are reasons other than gender for why people working in stores should not get the same pay rates as people working in warehouses.