Supporters of small and independent retailers have reacted with horror to the news that supermarkets have doubled non-food sales over the last five years.
More than a quarter of CDs (26.8 per cent) and DVDs (27.4 per cent) sold in Britain are bought in supermarkets, figures from TNS Worldpanel show.
Competitive prices and convenience are two factors said to be behind the trend.
Supermarkets' share of the CD and DVD markets has soared from 15.2 per cent and 12 per cent respectively just five years ago.
Nearly a fifth (19 per cent) of all clothing and footwear is bought in supermarkets - up from 11 per cent in 2001.
The large chains also now sell 12 per cent of all books, while their share of the computer games market has risen to 12.2 per cent from 5.4 per cent five years ago.
TNS Worldpanel research manager Lucy Burton said 37 per cent of newly-released DVDs were bought in super-markets compared to just 25 per cent from specialist high street stores.
She said: "Supermarkets are rapidly becoming a shop-ping destination in their own right for products such as DVDs and CDs, rather than them simply being added to the trolley with the weekly shop."
A quarter of newly-released DVDs are bought in nonspecialist high street stores followed by 12 per cent purchased online.
Ben Pinnington, spokesman for the Federation of Private Business, said that although they came as no surprise, the figures were still shocking.
"When you hear that £1 in every £8 in retail is spent at Tesco, you realise just how these large firms are cornering the non-food market," he said.
"With Tesco now trialing a non-food format in Stockport, it is becoming increasingly difficult for small, independent shops to compete.
"Undoubtedly this is putting the high street into crisis."
Mr Pinnington called on the Office of Fair Trade to launch a competition inquiry into the dominance of supermarkets.
This a was sentiment echoed by Len Griffin, who is company secretary of the Worcester-based Alliance of Independent Retailers.
"I understand that the Government is not keen to punish Britain's most successful company for being successful, but unless something is done it leaves independent retailers in a very difficult position," he cautioned.
"I would like to see a restriction on planning for large stores and the tactic of extending existing stores."
Last week the All Party Parliamentary Small Shops Group called for a moratorium on retail mergers and takeovers and an independent regulator to investigate the entire sector.
They also recommended the introduction of codes of practice, a review of the tax system and an end to the Jersey VAT loophole.
However, the British Retail Consortium said that the rise in non-food sales at supermarkets marked increased competition, which would benefit shoppers.
Dee Crooks, spokeswoman for the BRC, said: "The rise reflects that consumers have responded well to the one-stop shop concept.
"They have come to trust these brands and the price is clearly competitive.
"Supermarkets also tend to specialise in mainstream goods and are not specialist or niche, which is the preserve of independent retailers."
The TNS Wolrdpanel also showed that supermarket sales of clothing, footwear and entertainment products had risen by 94 per cent in the past five years. This outstrips the overall market growth of just 11 per cent.
The average price of an item of children's clothing sold in supermarkets is £2.68 - less than half the market average.
M ore than a quarter (27.3 per cent) of all child-renswear is bought in supermarkets.
The price of women's clothing sold in supermarkets rose by seven per cent on the previous year as the chains' own brands became stronger competitors to their high street rivals, TNS said.