Asda is to start consulting with staff over potential job losses next year which could total almost 2,500, according to sources.
Areas of work affected by any changes include petrol, bakery, back office and so-called hosting.
Jobs in the George areas of Asda stores could also be affected, it is understood.
The company declined to comment on any potential job cuts.
A statement said: "In a competitive retail market, where customers rightly expect great value and ease of service, we must always look at how we can work more quickly and efficiently for them - and, inevitably, that means we need to consider changing the roles we need our colleagues to do or the hours needed in particular parts of our stores.
"We believe the proposed changes we are consulting on would allow us to do a better job for our customers.
"We also recognise that discussions about potential change aren't easy. If the decision is taken to implement the proposed changes, we would work with our colleagues to look at the potential impact of these proposals on them."
Reporting by PA
