Sign or lose your job.

These are not the words Asda would use but it is, in essence, the position the supermarket is taking with thousands of staff who are resisting changes to the terms and conditions of their employment.

Two-years-ago Asda introduced a new contract which gave the company more control over when staff work and what they do.

Initially the contract was voluntary but in April this year Asda announced that it planned to impose it on the 60,000 staff who hadn’t yet signed it.

Under the new contract basic pay rises to £9 an hour but staff also lose paid breaks and will have to work some bank holidays. Night shifts will become shorter and the Asda reserves the right to change shift patterns “with reasonable notice”.

The GMB union says around 12,000 of its members are refusing to sign, as it stands they will leave the business at 23:59 on Saturday 2nd November.

Asda insists this number is “grossly exaggerated” but won’t say what the real figure is.

The company insists it has "full store rotas in place for all stores this weekend" and therefore won't struggle if staff are laid off.

Asda is following where other supermarkets have lead. Tesco and Sainsbury’s have imposed similar contractual changes on their staff in recent years.

The traditional supermarkets feel under pressure to make changes because of the change in people’s shopping habits. As we know, money is both moving online and into the pockets of the discounters, Aldi and Lidl.

Since the proposed merger with Sainsbury's fell through, there has been rumours Asda may try for stock market floatation. Credit: PA

Asda’s thinking is that by standardising contracts and demanding greater flexibility from its workforce that efficiency will improve and with it the company’s financial performance. The risk is that staff moral is undermined.

Asda’s owner, Walmart, also has one eye on a possible sale of the business. Walmart had agreed to offload the business to Sainsbury’s and ever since that takeover fell through earlier this year there have been whispers of a stock market floatation.

Asda believes it is being fair.

Staff retain a bonus (Sainsbury’s canned theirs), a minimum number of hours a week will be guaranteed, pay will be competitive if not best in class and only a minority of staff (3,000) will be left worse off financially.

If the past is a guide to the future then at the eleventh hour workers will sign, however reluctantly. If they don’t then Sunday morning will be interesting.