Brands that are not category leaders are under threat from the growing power of supermarket own-label products, the Competition Commission's inquiry has been told.

In its submission, the British Brands Group, which represents manufacturers, said it suspected "secondary" brands were being replaced by own-label products in major retailers' stores, and warned this could lead to restricted consumer choice.

"The fortunes of secondary brands warrant scrutiny as their role in the market has a direct bearing on competition," wrote BBG director John Noble.

"As the economic viability of secondary brands is impaired due to falling distribution, smaller retailers and their customers are deprived of an economic alternative."

A demise of secondary brands would also hit shoppers who use supermarkets, added Noble.

"If secondary brands were replaced by own-label, consumers would be less able to compare prices as different own-label offers are not comparable in the same way branded products are.

"Nor can own-label products always be directly and readily compared with branded products."

Noble also criticised the Commission for concluding there was no evidence of a decline in margins among suppliers, and argued the results of its own supplier survey showed otherwise.

"Sixty-seven per cent of respondents claimed gross margins had decreased over the past five years," he wrote.