SUPERMARKET chain Asda is threatening to sack tens of thousands of workers if they refuse to sign punishing new contracts, according to the GMB union, which represents them.

The Leeds-based chain, which is owned by US conglomerate Walmart, wants to impose compulsory bank holiday working and axe payment during rest breaks in order to fund a pay rise to a miserly £9 an hour.

Asda staff have voted overwhelmingly to reject the so-called “flexible” new contracts, dubbed Contract 6.

In May GMB members protested against the contracts at the firm’s Leeds headquarters. Now Asda has ramped up the dispute with its threat of sackings.

The contract had previously been voluntary for staff, but members now say they are being told they will lose their jobs if they don’t sign up, the GMB reports.

In a recent consultative ballot, 93 per cent of respondents told the union that they did not agree with the contract changes that were being forced on them.

GMB national officer Gary Carter said: “It’s a total outrage Asda bosses are threatening staff with the sack if they don’t agree to this flawed contract. Shoppers will be horrified to learn of what is going on behind the scenes.

“Our hard-working members are telling us they are being forced into signing these new contracts for fear of not being able to pay the bills or put food on the table for their kids.

“It’s sapping away morale and heaping misery on our members. Instead of strong-arm tactics, Asda needs to show some respect and listen to the workers whose hard work makes the company’s profits.

“The Asda workforce deserves a better deal and the company should get round the table with us and agree changes that would help both our members and the business thrive.

“Asda is a multibillion-pound company, it doesn’t need to bully staff out of their hard-won terms and conditions.”

Asda workers from across the country will gather at City Square in Leeds city centre at noon on Wednesday August 14 in a protest against the contracts.

Mr Carter said: “This demonstration will send a loud and clear message to Asda that, however much pressure management has put on staff to sign, workers believe Contract 6 is still not good enough.

“The new contract cuts holiday entitlement, slashes bank holiday and night-shift pay and introduces an any time, any place, anywhere culture which risks a hugely damaging impact on the predominately part-time, low-paid, female workforce, who need flexibility that works for them.

“We’re calling on Asda to come back to the negotiating table and give this dedicated workforce a fair deal.”

Asda decided to enforce the new contracts after a proposed merger with rival supermarket Sainsbury’s was ruled out by competition regulators in April.

An Asda spokesperson said: “This new contract will see Asda invest in a pay increase for over 100,000 retail colleagues, as well as enabling us to deliver better service to our customers in an intensely competitive marketplace.

“We are continuing to talk to our colleagues about this change and to understand what it might mean for their individual circumstances.”

Asda employs 128,000 staff at 259 stores and 19 depots across Britain.

The supermarket’s roots stretch back to the 1920s when farmers in the old West Riding founded a dairy company that became Associated Dairies.

Following a series of mergers which started in 1949, Asda was founded on May 3 1965 and was taken over in 1999 by the Walmart conglomerate.

The chain, one of the “big four” supermarket companies, is currently the second-biggest by market share behind Tesco.