The data from market researcher Kantar Worldpanel on Tuesday showed the fastest overall sales uplift since March, boosted by warm weather, with promotional sales dropping to their lowest level since September 2010 as the biggest chains shift towards more simple pricing models.

"The sun’s eventual appearance was a welcome boost to the market after a delayed start to the summer," said Fraser McKevitt, Kantar Worldpanel's head of retail and consumer insight.

Recent sales trends continued, with German discounters Lidl and Aldi recording growth of 12.2 percent and 10.4 percent respectively and winning market share.

Tesco was the best performer of Britain's big four supermarket chains, with sales down 0.4 percent.

"Current trends suggest the retailer may return to (total sales) growth this year, which would mark the end of a decline stretching back to March 2015," said McKevitt, highlighting the success of Tesco's own-label Farm brand launched this year.

Sales at Tesco's closest challenger, Sainsbury's, dipped by 0.6 percent, while store closures contributed to a 1.8 percent decline at No. 4 player Morrisons.

Wal-Mart's Asda, Britain's third-biggest supermarket chain, remained the sector laggard with sales down 5.5 percent.

Kantar Worldpanel said there was no evidence of Brexit-fuelled inflation causing food prices to rise.

Grocery price inflation remains negative, it said, with a representative basket of goods 1.3 percent cheaper than it was last year.

Falling prices reflect the impact of Aldi and Lidl and the market’s competitive response, as well as deflation in some major categories such as bacon, detergents, snacks and butter.

Official data for July, published last week, showed retail sales jumping much more than expected, adding to signs that there has been little immediate hit for consumers from June's surprise vote to leave the European Union.

(Reporting by James Davey; Editing by David Goodman)