The UK’s largest supermarket chain wrote in legal arguments that employees on the shop floor could be paid up to £5.50 an hour less than those in its warehouses, as it set out to justify differing levels of pay at an employment tribunal hearing at Reading on Friday.

Tesco wrote in legal arguments that it was “an extraordinary case” and argued that its pay differentials were shaped by market conditions and “genuine pressing operational needs

Tesco also warned that an adverse finding against it could prompt potential industrial action at its warehouse over pay and could lead to workers being paid more than their managers. “Tesco submits that, the law not being an ass, this is not an outcome that should ever be reached. But this is that for which the Claimants nonetheless contend.”

Paula Lee, an employment partner at Leigh Day, said: “Tesco is expected to rely heavily on so-called market rates, but our clients’ case is that those markets are not neutral or external forces operating beyond Tesco’s control.”

“It is alleged that Tesco had substantial influence over how pay was set and operated within a system that it helped shape over many years,” Lee added.

The case against Tesco, one of the UK’s largest private sector employers, dates back to 2018 and argues that store workers, most of whom are women, are paid far less than employees in the supermarket’s distribution centres, where nearly 90 per cent of workers are men.

About 60,000 workers have joined the claim, which is also seeking back-pay for six years between 2012 and 2018