UK retailers with a "clear price message" are enjoying the strongest sales in the market, according to the latest data released by research analysts TNS.

The figures, released yesterday (19 August), showed discounters Aldi and Lidl are continuing to see double-digit sales growth, while among the so-called "Big Four", Asda and Morrisons gained share.

Aldi sales were up 19.8% during the 12 weeks to 10 August; rival Lidl saw sales rise 12.3%. Asda, the UK's second-largest retailer, enjoyed sales growth of 8.5%, while Morrisons increased sales by 9.4%.

Tesco and Sainsbury's, meanwhile, saw sales rise - but slower than the UK grocery sector as a whole, TNS said. Tesco's sales were up 6.5%, while Sainsbury's saw sales climb 5.3%. Total grocery sales were up 7.2%, thanks, TNS said, to inflation, with volumes "effectively static".

Ed Garner, director of research at TNS, noted Aldi and Lidl's "strong growth" and Aldi's record market share of 3%. However, he said Aldi's growth is being "entirely driven" by new stores and new shoppers.

"Spend levels for existing shoppers remain unchanged and quite low compared to the top four," Garner said, pointing to a typical monthly spend per household of GBP45 (US$83.51) at Aldi, compared to GBP126 at Tesco.

Garner added: "Several commentators have stated that 'the middle classes are flocking to the discounters'. In fact, new shoppers are predominantly younger households with children, which is more logical - their budgets will have come under strongest pressure."