Bhoo Patel, owner of Philog Stores on The Philog, said that he believed Tesco had earmarked about 20 sites in the Welsh capital for its Express developments within the next 18 months.
Bhoo said: "I think Tesco is trying to blast independent retailers in Cardiff ahead of the findings of the Competition Commission inquiry."
He said that three Tesco Express stores were due to open within a one-mile radius of his store within the next couple of months. Bhoo admitted that independents had been slow to react to the arrival of Tesco Express but said that was because no one had expected it to be on such a large scale.
He has started a petition against a proposed Tesco Express store in the Philog area and has received 400 signatures in the first week. He is now seeking support from other independent retailers, wholesalers Booker and Capper & Co and local politicians in a bid to fight some of the proposed developments.
A spokeswoman for Tesco said that the figure of 20 stores was "not the case" and that "as you would expect we always look at new sites but inevitably many don't come to anything".