Tesco says that customers have been buying more food during fewer shopping trips amid the coronavirus pandemic.
The supermarket said that while the number of trips made by shoppers fell by nearly a third in the 13 weeks to 30 May, the amount being bought rose 64%.
In a trading update, Tesco said group sales had risen 8% to £13.4bn in the period, but warned coronavirus-related costs were set to hit £840m this year.
Tesco's boss said it had been "a very challenging period for everyone".
Like many of its rivals, Tesco was forced to overhaul its strategy in-store and online amid the coronavirus lockdown.
Tesco chief executive Dave Lewis said: "In just five weeks, we doubled our online capacity to help support our most vulnerable customers and transformed our stores with extensive social distancing measures so that everyone who was able to shop in store could do so safely."
The supermarket says that it saw a substantial increase in costs as a result. They stemmed from offering 12 weeks' paid leave to 26,000 vulnerable workers and recruiting 47,000 temporary staff to cover sickness and meet demand.
Across its UK & Ireland business, sales rose by 9.2% in the three months to 30 May. Online sales mainly drove the increase, jumping by 48.5% in the quarter.
As more customers turned to online shopping, the firm ramped up online delivery slots and is now fulfilling more than 1.3 million online order per week.
In UK stores, food sales also increased by about 12% as customers "focused more on the purchase of their essential items".
Mr Lewis said that coronavirus-related costs had been "only partly off-set" by the sales boost and business rates relief.
Tesco said it had benefitted from rates relief worth about £532m under the measures offered to shops in England, Scotland and Northern Ireland.