The Confederation of British Industry released its retail sales balance data on Thursday. The CBI retail sales balance dropped to 29% in June from 51% in May.
The decline was driven by a drop in grocery sales as the supermarket price wars continue.
Sales expectations for next month eased.
CBI Distributive Trades Survey Chairman and Asda's Chief Customer Officer, Barry Williams, said that retailers hope to purchase more in the summer months.
"Low inflation - expected to stay below 1% throughout this year - has given customers more discretionary income. The power of the pound in their pocket is going further and shoppers are spending more on treats, like flowers and jewellery, as well as on activities with their families," he added.