Consumer spending fell to a record low in July despite hot weather, according to new figures.
The British Retail Consortium (BRC) and KPMG reported just a 0.5% increase in retail sales in the year to July.
They claimed that slow real wage growth and continued uncertainty surrounding Brexit were to blame for the slump.
Typically, hot weather results in a boost for consumer spending, with shoppers updating their wardrobes and buying more food and drink. However, online non-food sales rose 3.7% compared with 7.5% in July last year. Similarly, KPMG's UK head of retail, Paul Martin, said "another category which has historically benefitted from the good weather is grocery, but even here sales are lacklustre, which is a cause for concern".
Helen Dickinson, the BRC's chief executive, warned that a "combination of slow real wage growth and Brexit uncertainty has left consumer spending languishing".
While the UK has seen real-term wages accelerate in recent years, they still remain below the levels seen before the financial crisis began in 2008. In May this year, the average weekly pay adjusted for inflation was £468, compared with the £473 average in April 2008.
Ms Dickinson said: "The challenging retail environment is taking its toll on many High Street brands who must contend with rising import costs, a multitude of public policy costs and ever-higher business rates."