Asda could axe 2,500 jobs next year as it reshapes its workforce amid a “competitive retail environment”.

The supermarket giant has launched a consultation on roles across the business, which will include workers in its head office, bakery and petrol forecourt functions.

Staff working in George departments within Asda stores could also be impacted.

Any redundancies resulting from the consultation would come into force next year.

Asda is in the midst of a proposed merger with big four rival Sainsbury’s, which is the subject of a probe by the Competition and Markets Authority.

But the Walmart-owned grocer insisted the potential changes, which could involve alterations to employees’ roles and working hours, would allow it “to do a better job for our customers”.

A spokeswoman 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.”

The GMB union described the proposed job losses as a “hammer blow” and slammed Asda for the “appalling” timing of the announcement, in the run-up to Christmas.

GMB national officer Gary Carter added: “Asda is performing well and is highly profitable because of the hard work of our members, who are the backbone of the company.

“These cuts make no sense whatsoever – slashing our members’ jobs would hurt the service Asda customers receive. GMB will fight tooth and nail for every single job.

“With all the speculation surrounding the proposed Sainsbury’s merger and potential sell-offs of stores, this news will not put anyone’s mind at rest.”