Despite his insistence that small retailers should stay clear of the Competition Commission's investigation, OFT boss John Fingleton admitted one exception was where they had evidence that planning issues were hindering their attempts to grow and become more competitive. If they did, they should step up to the table, the Irishman said.

"That type of evidence is what the CC will find extremely useful," he said. "Where these businesses have tried to do things to attract more people and tried to compete more, but planning issues have thwarted them, the CC will want to listen."

Planning remains the central issue within the OFT's decision to refer the industry to the CC, added Fingleton, with other concerns cited as supermarket buying power, below-cost selling, price-fixing and price-flexing. "Planning has not been looked at before, whereas the pricing issues have. The CC looked at pricing seven years ago, but never planning."

A move from 'sufficiency of need' to 'sufficiency of competition' could be one outcome, which would mean a relaxation of laws to encourage new entrants.

Among the OFT's concerns are allegations that major retailers are buying up land and leaving it undeveloped in a bid to prevent rivals from opening stores. However, Booths chairman Edwin Booth said that scrutiny of such claims could expose c-store owners pursuing similar tactics to those of the big four supermarkets.

He said: "I know of Nisa-Today's members who have bought land to prevent a rival from building a store on it."