Nisa chiefs described the sale of the supermarkets in West Belfast and Dungannon as "sad", while the Northern Ireland Independent Retail Traders Association (NIIRTA) was concerned the move would reduce consumer choice.
In the light of the sale, Nisa-Today's chief executive Neil Turton called for the Office of Fair Trading to "reassess the current competitive status within the retail sector" in a bid to prevent further erosion. He added: "Nisa-Today's is sorry to see Curley's sell to a major UK business. It is sad for Northern Ireland's retail scene to see a strong local brand taken over by a UK multiple."
Turton added that the sale would not have a material affect on Nisa-Today's buying power, or influence on the independent retail sector.
NIIRTA chief executive Glyn Roberts said he understood that the Kennedy family, owners of Curley's, had made a commercial decision, but added: "It's disappointing that one of our largest independent local retailers is being sold to one of the big multiples. Multiple retailers in the rest of the UK have long adopted the practice of buying successful competitors out of the market place. We are concerned that more and more of our independent retail sector will be lost in this way, removing local choice."
Curley's, which trades under the slogan 'Buy local - we do', retains ownership of its 11 off licences. Managing director Hugh Kennedy said he believed Sainsbury's provided the "most appropriate offer" for customers and employees.