From forcing farmers into penury, to concreting over large swathes of land, to binge drinking, the retail giants, once hailed as a beacon of convenience, have recently faced an onslaught of criticism.

While most of us still rely on supermarkets, talk of food miles and excess packaging means the weekly shop is done with increasingly guilty consciences.

Yesterday it was the turn of the National Consumer Council. According to the watchdog, the credit crunch has sparked a dramatic increase in the promotion of cheap and unhealthy food. Morrisons was singled out as the worst offender, with 63 per cent of its in-house promotions featuring sugary or fatty foods, but none came out of the survey particularly well.

The British Retail Consortium was quick to refute the report, claiming the figures which compared the run up to Easter this year with July 2006 were misleading and ignored the increase in cheaper fresh fruit and vegetables. But with another survey confirming the decline of the healthy five-a-day, the lasting image is one of supermarkets forcefeeding customers cut-price chocolate slices to avoid a large dent in profits.

"In the last 12 months alone, food inflation has reached a record high of 13.7 per cent and as many families come under increasing financial strain, nearly one in five parents are turning to cheaper, frozen and convenience food options," says Katie Roswell from PruHealth. "Two-thirds think healthy foods are simply more expensive."

Even when supermarkets do respond to customer demands and cut prices of essentials, the reaction is rarely good. After Asda, Tesco, Morrisons, Sainsbury's were last year accused of colluding with dairies to keep the cost of milk, cheese and butter artificially high, news two of the big five were to cut prices was greeted with equal criticism. Dairy farmers last month described the move as a nail in the coffin of an already struggling industry.

Recognising the concerns over supermarket dominance, the Competitions Commission embarked on a two-year inquiry, but concluded there was no evidence that supermarkets harm smaller, independent traders and, in fact, benefited consumers. Branded a whitewash in many circles, the report was widely seen as a green light for the continued march of retail giants.

"It's simply a myth that supermarkets make excess profits at the expense of their suppliers," says a BRC spokesman. "Most of the benefits of supermarket growth have been reinvested into lower prices, new products and bigger, better stores and there is no evidence that the intense competition between supermarkets has been carried by their suppliers.

"Small retailers are vital to consumer choice, the richness of our high streets and local economies and the number of traditional retailers like greengrocers, bakers and butchers has actually gone up in recent years. In 2005 there were 43,800, by last year the number had grown to 51,700.

"People talk of clone towns dominated by well-known retailers, but it's too simplistic to say these clones have declared war on independent shops.

"There are a host of reasons why smaller shops go out of business, from high rents to expensive town-centre parking, and the growing burden of regulation and red tape."

If supermarkets have been absolved from ruining the traditional high street, their green credentials are perhaps harder to justify. While most have made much of their decision to cut down on plastic bags, the environmental impact surely has to be negated by the amount of food imported from abroad?

"Environmental experts have admitted food miles are a simplistic way to measure the environmental impact of food distribution," says the BRC spokesman. "It is certainly possible to argue that moving large volumes of food in full vehicles is less damaging than moving small volumes over shorter distances.

"When it comes to things like carrots, beef and lamb, the produce stocked by supermarkets is overwhelmingly British. However, sometimes it may also be less damaging to the environment to import foodstuffs like tomatoes from Spain than grow them under protected conditions over here. Also it's important to note that while there was a rapid growth in air freight during the 1990s this has now levelled off.

"It's understandable that supermarkets attract a lot of interest, but sometimes the assumptions made are ill-informed or just plain wrong."