Pret A Manger is permanently closing 30 of its outlets as a result of "severely declining sales", putting around 1,000 jobs at risk.
The sandwich shop chain says it has faced "significant operating losses" due to the coronavirus pandemic which has forced the closure of many high-profile retailers.
Pret A Manger closed all of its 410 UK shops in March but has gradually been reopening them, with 339 now operating once more.
However sales have not recovered and are down 74% on this time last year.
At least 1,000 jobs are reportedly at risk from the mass closure, which will happen before the end of the year.
The company will also be reducing the number of workers in its remaining outlets and support teams will undergo restructuring.
A sale process will be started for the lease of its main support office in London Victoria.
Pret chief executive Pano Christou said: "It’s a sad day for the whole Pret family, and I’m devastated that we will be losing so many employees. But we must make these changes to adapt to the new retail environment.
"Our goal now is to bring Pret to more people, through different channels and in new ways, enabling us to grow once more in the medium term."
Details of the stores affected have not been published.
