Retailers have criticised new curbs on supermarket dominance of the grocery sector with one of the "big four" warning they could lead to higher prices for consumers.
The Competition Commission unveiled a planning shake-up in a bid to boost competition in the £95 billion grocery market.
The culmination of the two-year probe into the sector will see a new competition test in planning decisions on larger stores as well as action to prevent land agreements restricting competitors from entering the market.
It also recommends a new independent ombudsman who will enforce a strengthened code of practice to protect suppliers, governing all grocery retailers with a turnover greater than £1 billion.
The UK's four biggest supermarkets - Tesco, Sainsbury's, Asda and Morrisons - all came under scrutiny in the investigation.
Asda chief executive Andy Bond said: "The commission's proposals on the new code and an ombudsman could cost the industry hundreds of millions, leading to higher prices for customers which will hit families hard at a time when they are already feeling the pinch," he said.
Tesco chief executive Sir Terry Leahy said: "We are not sure that the main recommendations will improve the life of the British consumer."
New Economics Foundation policy director Andrew Simms, who wrote Tescopoly, a book about Tesco's dominance of the grocery market, said the commission's recommendations would "almost certainly not" lead to a more open market.
The British Retail Consortium warned the Government against introducing legislation that would hamper healthy competition and add to costs.
It added to criticisms of an ombudsman, saying "there can be no justification for a multi-million pound quango which would ultimately be paid for by customers".
