Sales growth at British supermarkets picked up in September, reflecting an unseasonal heatwave, industry data showed on Tuesday.

Market researcher NIQ said the total value of UK grocery sales rose 10.3% year-on-year in the four weeks to Sept. 9, having been up 7.2% in its August report when wet weather held back sales growth.

NIQ highlighted strong sales of meat, fish and poultry as well as salad vegetables.

It noted that sales volumes in the week to Sept. 9 were up 2.1% - the first increase since early May, suggesting improved consumer willingness to spend.

The NIQ data going into September provides the most up-to-date snapshot of UK consumer behaviour.

Britain's consumers have largely defied high inflation and rising borrowing costs to keep up their spending in 2023, but there are signs that the economy is weakening.

NIQ said there was a polarisation of purchasing power.

Its survey data showed 44% of UK households were impacted only a little or not at all by the increased cost of living yet 56% of households were moderately or severely affected.

Echoing data from rival market researcher Kantar last week, NIQ said discounters Aldi and Lidl were again the fastest growing grocers over the 12 weeks to Sept. 9, with sales up 19.6% and 16.6% respectively, giving a combined market share of 20.2%.

Market leader Tesco and Marks & Spencer were the only other retailers to grow share.

Looking ahead, NIQ forecast total grocery sales growth of around 7% in the fourth quarter and volume growth at food retailers in December. (Reporting by James Davey; editing by Christina Fincher)