A coalition of environmentalists, farmers, shopkeepers and Women's Institutes is demanding an official investigation into the domination of the grocery market by the big supermarket chains.
The call comes a month after Sainsbury's took over 114 Jacksons stores, and reflects disappointment among consumer groups with the two year-old supermarket code of practice. Tesco currently controls 28 per cent of the grocery market.
Friends of the Earth, Farm, the Association of Convenience Stores and the National Federation of Women's Institutes want the Office of Fair Trading to investigate the impact of market concentration on small shops, farmers and consumer choice. They also want the OFT to impose a ban on further takeovers of convenience stores by Tesco, Sainsbury's, Morrisons and Asda.
The OFT last investigated the big four's hold on the market in 2000.
Friends of the Earth campaigner Sandra Bell said: "The OFT has turned a deaf ear to our concerns about the loss of small shops and bullying of suppliers."