Lawyers representing staff of Next in a claim for equal pay have accused the clothes retailer of destroying key documents ahead of the case – something denied by the company.

Leigh Day, which is representing 330 members of staff – largely women – who say they have been underpaid, claims that “vital documents needed to help store staff prove their ongoing equal pay claim” have been destroyed by Next.

“It appears that essential documents to our case have been destroyed,” said Elizabeth George, a barrister at the law firm.

She added: “I can say that it is fundamental to a fair hearing of this case that neither side destroy documents that they know (or should know) are highly relevant to the other’s case.”

The lawyers will bring up their claims at a one-day hearing at the Employment Tribunal on January 12 next year. This will decide whether Next should be punished for the potential destruction of the documents.

However, Next denied any wrongdoing.

“Next has not destroyed documents in breach of a Tribunal Order and it believes that any assertion that it has, is based upon inaccurate information,” it said in a statement.

“Next is therefore confident that any application for a ‘Strike-Out-Order’ will not succeed, as it is meeting all of its obligations under the Tribunal process.

“Next will continue to defend itself vigorously in this claim and it would be inappropriate to comment further at this stage, as it is an ongoing legal process.”

Staff in Next stores, who are mainly women, say they are paid between £2 and £6 less per hour than their colleagues who work in Next’s warehouses.

The warehouse staff are largely men and their jobs are no less demanding, the claimants say.

“When I was told exactly how much higher the warehouse pay was, I was shocked and angry and felt extremely undervalued,” said one of Leigh Day’s clients, who has asked not to be named.

“To find out now that Next may have destroyed important documents is yet another blow. I feel angry and betrayed and have now lost all respect for the company.”

Leigh Day has similar claims against Asda, Sainsbury’s, Morrisons, Tesco and the Co-op.

Ms George said: “The Equal Pay Now campaign is about bringing store staff from different retail sectors together, so that they do not feel theirs is an individual fight because that is pretty daunting.

“We have one focus, ending the unequal pay that applies between the stores and the warehouses for men and women doing equal work.”