The return of cooler weather and exodus of people on summer holidays contributed to UK supermarket sales slowing during August, according to a new report.

Retail data released by Nielsen revealed that supermarket sales increased 2.5% compared to a year earlier in the four weeks ending 12 August, considerably slower than the 5.1% expansion in the preceding month.

Sales of soft drinks and fresh produce saw marked falls, with both categories' annual comparisons suffering as a result of a heat wave at the end of July 2016.

In contrast, cooler weather provided a boost to sales of confectionary and packaged grocery products.

"It's a bit of a reality check after two months of really impressive growth, as shopping patterns were disrupted by the return of cooler weather and people going on their summer holidays," said Mike Watkins, UK head of retail and business insight at Nielsen.

"Although the market has recovered from the low-point 12 months ago, the return of inflation and rising concerns about the economy mean the weekly grocery shop is now the most popular target for people to cut down on household expenses.

"Thirty percent of Britons now admit to buying cheaper grocery brands to save money."

In the 12 weeks to 12 August, Tesco saw the biggest rise in sales among the so-called "big four" supermarkets at 3.2%, followed by Morrisons at 2.2%, Sainsbury at 1.8% and Asda at 1%.

German discount chains Aldi and Lidl, which have been rapidly gaining market share in recent years, saw sales jump 14% and 20.5%, respectively.

Watkins said shoppers were still willing to spend to purchase affordable indulgences in food and drink, despite their intention to save money.

"Maintaining promotional activity will be key to supermarkets increasing sales in the coming months in the absence of any seasonal events or the return of hot weather," he said.

"The key for retailers in differentiating their brand in consumers' eyes is through better customer services and making shopping easier and more convenient for their customers."