The Competition Commission's investigation into the grocery market is building momentum - and a string of critics of the big supermarkets is leaving the inquiry team in no doubt about the problems facing smaller retailers.
Earlier this month a top-level wholesalers delegation, including FWD director general John Murphy, Booker CEO Charles Wilson and Today's Group MD Rodney Hunt, attended a hearing with the Commission.
The group told the inquiry team that wholesalers' feedback suggested the price gap between Tesco and other retailers on various products had widened since the last Competition Commission grocery market report in 2000.
The gulf had grown from 11% to more than 15% in some cases, indicating that Tesco's unfair buying advantage had increased, they claimed.
Murphy said the group had also alleged that big supermarkets used extensive legal resources to bully local councils on planning issues. "We argued that the Commission's focus on planning should be widened to address that."
The ACS said it was due to meet the Commission on 26 September to address topics including buying power and abuse of the planning system.
Director of public affairs James Lowman said the ACS was considering referring to moves to liberalise planning laws to make out-of-town sites easier to develop. He highlighted the interim report on the Barker Review of Land Use Planning issued in July, which suggested making it easier for major retailers to build out-of-town stores.
Lowman added: "That would only exacerbate the market power and monopoly of the supermarkets."
Another leading contributor to the Competition Commission's investigation from the independent retail sector said he and other representatives of the sector were also stressing the danger of liberalising the planning system.
He added that the Commission had been criticised in many quarters for making the draft questionnaire to suppliers too simplistic. He said that it contained many fewer questions than the one that had been sent out to retailers, so some feared that it would not cover all the issues in enough detail.
Meanwhile campaigners from pressure group Tescopoly said they planned to take people affected by supermarkets - including one ex-supplier - along to their Competition Commission inquiry hearing on 11 October.
Spokeswoman Judith Whateley said: "We want to give evidence via people that have experience locally of how Tesco hasn't played by the rules."
Friends of the Earth, which gave evidence to the Commission this week, said it was frustrated that the Commission only wanted to hear evidence of problems and not solutions.
Senior campaigner for food and farming Vicki Hird said: "They're thinking purely about how supermarkets affect competition and are looking for evidence rather than remedies.
"We want them to think more broadly about how their recommendations will have an impact on other areas, so for example how weakening planning guidance would affect people's welfare if they weren't able to access shops."