Aldi, Lidl and Netto, the discount supermarkets, are forecast to increase their share of Britain's grocery market by 60 per cent over the next four years as the middle classes trade down because of the credit crunch.

A new report claims that the discount chains will generate nearly £7.5billion of sales in 2012, compared with £4.5 billion last year.

Joanne Denney-Finch, chief executive of the Institute of Grocery Distribution (IGD), said: “The UK discount market will continue to grow as discount retailers reap the benefits of a more price-conscious environment.

“Growth will not only be fuelled by worries about the economy; discounters are giving consumers more of what they want in terms of healthier and more upmarket ranges.”

Aldi and Lidl have been the biggest beneficiaries of the consumer slowdown that has changed the way that Middle England shops for food. Marks&Spencer said last week that it was losing market share as customers “traded down” to cheaper rivals.

Aldi, which claims to be up to 20 per cent cheaper than its rivals, plans to open a store a week to take advantage of the pressures on homeowners. Aldi and Lidl have taken out repeated advertisement s in Estates Gazette, the property magazine, offering agents incentives to find sites to meet the growing demand for cheaper goods.

The IGD forecasts that Aldi will have at least 530 stores in the UK by 2012, compared with 373 today, while Lidl will have 610.

Tony Baines, Aldi buying director, told The Times that the German-owned chain was luring customers from M&S and Waitrose as well as Tesco and Sainsbury's. He said sales were running 30 per cent ahead of last year. “We were a bit of a hidden gem in the 1990s,” Mr Baines said.

“As we are approaching 400 stores we have got a critical mass with stores in most population centres. We have our product offer absolutely right now.

“We have doubled the amount of fruit and vegetables in our stores and put far more focus on fresh ranges.”

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