Tesco has revealed plans to make operational changes at Metro stores and a small number of Express branches, which are expected to lead to 4,500 job losses.

Tesco said it intends to “simplify and reduce processes and administrative tasks” at its 153 Metro branches as it seeks to run the business “more sustainably in an increasingly competitive and challenging retail environment”.

The leading grocer said the changes will enable it to run stores in a way that reflects how customers are shopping in them. Tesco said the Metro format was originally designed for larger, weekly shops, but now almost 70% of customers use them for convenience shopping.

Tesco intends to fill shelves faster with fewer products stored in back rooms and more going straight to the shop floor.

Staff will work “more flexibly across the store to improve customer service at the busiest times of the day and in the right areas of the store” and there will be a “leaner” management structure.

Tesco UK and Ireland chief executive Jason Tarry said: “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.

“We do not take any decision which impacts colleagues lightly but have to make sure we remain relevant for customers and operate a sustainable business now and in the future.”

Changes are also being made in 134 lower-footfall branches of Tesco’s 1,750-strong Express estate, such as reduced opening hours at the start and end of the day.

Tesco hopes to find alternative roles for those affected but said: “We expect that these changes will lead to an overall reduction of around 4,500 colleagues.”

Shop workers’ union Usdaw, which has 160,000 members at Tesco, said it would begin collective consultation with the grocer immediately and demanded government action ”to tackle the crisis in retail”.

Usdaw national officer Pauline Foulkes 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.”