Grocery sales were flat over the last three months when turnover declined at all of the big four grocers.

Hot weather last year and low like-for-like price rises kept a lid on growth in the 12 weeks to August 11, the latest Kantar grocery industry data showed. Inflation over the period was 0.9%.

However, discounters Aldi and Lidl, alongside online specialist Ocado, which was the fastest-growing grocer, all achieved strong revenue rises.

Tesco’s sales slipped 1.6% in the period, while its market share inched down from 27.4% to 27%.

Asda’s sales fell 1.5% and its market share slipped from 15.2% to 14.9%.

Morrisons’ sales were down 2.7% while its market share edged down from 10.3% to 10.1%.

Sainsbury’s revenues fell 0.6% and its market share was 15.4% versus 15.5% in the comparative period last year. That made Sainsbury’s the strongest performer among the big four since November 2017. The retailer was helped by sales of branded goods up 1.5%, more promotions and price lockdowns.

Lidl’s sales rise of 7.7%, helped by store openings and 489,000 additional shoppers, gave it a record market share of 5.9% – up from 5.4% last year.

Aldi accounted for 8.1% of the market after sales advanced 6.2%.

Ocado increased sales by 12.6%. Its market share rose from 1.2% to 1.4% and it accounted for 18% of all online supermarket sales.

Kantar head of retail and consumer insights Fraser McKevitt said: “July’s hottest day on record wasn’t enough to shift the market into growth but the grocers will have been encouraged by glimpses of better weather during the past four weeks which helped boost sales of summer staples.”