The Warehouse chief executive Mark Powell claims his rivals are stopping it from selling some high-end branded products.
Mr Powell says he is looking into whether his competitors' actions are legal under fair trading laws.
He says The Warehouse is introducing some higher end Sony and Kambrook products into its stores after it bought the appliance and electronics retailer Noel Leeming in December.
However he says some brands are prevented from selling their products at his stores because rivals don't want the competition.
"There are definite restrictions and threats put on suppliers by our competitors. I can't prove that (but) I know it and it happens."
Mr Powell says overt pressure has been put on suppliers in the past, and that is still going on, creating a situation that is not good for customers.
Meanwhile, Mr Powell says sales from flagship stores will play a smaller part in the business as the group's other brands grow.
"Traditionally The Warehouse - the red shed - has been 90% of the group's sales. We see that declining over the next three to five years to be less than 60% or so of the group's sales."
Mr Powell says it will become a true multi-business trading group and each of the businesses in the portfolios will have different growth curves. The Warehouse and Noel Leeming will have about 3% growth and Warehouse Stationery has a greater growth potential.
He says the group's multichannel offering is expecting sales growth of 25% - 50% over the next year.