Supermarket giant Tesco says about 4,500 staff in 153 Tesco Metro stores are set to lose their jobs in the latest round of redundancies.
The UK's largest grocer said changes to the way the stores operated would "serve shoppers better" and help to "run our business more sustainably".
It said the stores were operating in an increasingly competitive and challenging retail environment.
Tesco boss Jason Tarry said the firm did not take the jobs decision lightly.
The company said the Metro format was originally designed for larger, weekly shops, but now nearly 70% of customers used them as convenience stores, buying food for that day.
Tesco, which employs about 340,000 people in the UK and Republic of Ireland, said that changes to the stores would now include:
"faster and simpler" ways of filling shelves, with fewer products stored in the back rooms and more stock going straight to the shop floor
staff working "more flexibly" across the store to improve customer service at the busiest times of the day and in the right areas of the store
"leaner" management structure.
"In a challenging, evolving retail environment, with increasing cost pressures, we have to continue to review the way we run our stores to ensure we reflect the way our customers are shopping and do so in the most efficient way," Mr Tarry added.
It is also making some changes in 134 of its 1,750 Express stores, where customer footfall is lower.
Changes in those stores will include "a slight reduction in opening hours during quieter trading periods at the start and end of the day, and simplifying stock routines".
Tesco is in the midst of trying to save £1.5bn as the competition between supermarkets intensifies. It comes as German budget rivals Aldi and Lidl continue to put pressure on the big four supermarkets.
In January, Tesco announced it would close food counters in 90 of its stores as part of a wider cost-cutting plan that would affect 9,000 staff.
Pauline Foulkes, Usdaw national officer, said: "Our members at Tesco are shocked and dismayed by yet another round of potential job losses, coming just months after 9,000 staff were put at risk in stores.
"We will be working hard to make sure that any members potentially affected by these proposals are supported at this difficult time and throughout the consultation period.
"This issue is not confined to Tesco, our High Streets are in crisis, with jobs being lost due to shops closing, retailers folding and businesses engaging in significant restructuring to survive.
"We need the government to address the worries and concerns of shop workers and our members."
Source: BBC News