Retail sales fell at their fastest rate for over four years this month, according to the Confederation of British Industry (CBI).
CBI's Distributive Trades Survey found sales volumes fell faster than at any point since January 2012. Weak consumer confidence after the Brexit vote was likely the largest factor contributing to the decline, CBI said.
Orders to suppliers fell at the quickest rate since March 2009. CBI said they expect further decline in August.
Grocers, furniture and carpet store performed particularly badly in the retail sector. Non-specialised department stores, footwear and leather goods posted higher sales volumes.
Rain Newton-Smith, CBI chief economist, said: "While conditions in the retail sector have weakened, we should be careful about reading too much too soon, as consumers were likely to err on the side of caution in the immediate period following a vote to leave the EU.
"Current low levels of inflation and high overall employment should support consumer spending in the near term, although the impact of lower sterling is likely to feed through to higher inflation over time.
"What businesses and consumers need now is calm and decisive leadership, a clear timetable and a plan for negotiating the UK's future outside the EU to restore confidence."