Vic Grewal, who owns Budgens in Flackwell Heath, Buckinghamshire, said that his store would be "finished" if the multiple-owned c-store was given the go-ahead.
The survey, conducted by property agents Colliers International on behalf of the owners of the site, claimed that local businesses would not be affected by the introduction of the Sainsbury's store.
It stated: "The impact assessment has demonstrated that a new convenience retail operator at the site would not result in the closure of any existing operators and would not adversely affect the vacancy rates of the centre."
The report added that Vic's store would "remain viable" and could even see a minor increase in turnover. It said: "The proposed development of a local convenience store on the application site would not have an adverse impact on town centre viability, and would have a positive impact on local consumer choice and the range and quality of the retail offer."
However, Vic believes the Sainsbury's would destroy his business. "It's a simple equation; there's a fixed number of customers in a town and if a new store is introduced that will take some of them away," he said. "We're just breaking even at the moment and another store could cost us up to 20% of business."
Vic added that the survey should have been carried out by an independent party as Colliers International is retained by Sainsbury's for all of its store development, acquisition and extension work.