Total sales fell 3.1% in April compared to the same month last year, according to the British Retail Consortium (BRC) – the biggest decline since its survey began in January 1995.
On a like-for-like basis – comparing sales in stores that have been open for more than a year – there was a fall of 4.2%, the sharpest since April 2005.
The BRC said the slump partly reflected the timing of Easter holidays, which started in April last year and in March this year, but also indicated a weakening trend for the sector.
Paul Martin, head of retail at KPMG, which compiled the data, said: “April’s figures show retail sales growth falling off a cliff.”
BRC chief executive Helen Dickinson said even taking into account seasonal distortions “the underlying trend in sales growth is heading downwards”.
The high street has been under increasing pressure from the squeeze on household incomes as inflation outpaces wage growth, which is only just coming to an end, while the extreme cold weather seen earlier this year has done little to help.
Retailers Toys R Us and Maplin have already gone bust this year and chains including New Look have been closing stores.
Ms Dickinson said of the April figures: “The first glimpse of summer may have temporarily lifted clothing and footwear, but non-food sales overall continue to be weak.
“Consumers’ discretionary spending power remains under pressure and the reality is, that with only a gradual return to solid growth in real incomes expected, the market environment is likely to remain extremely challenging for most retailers.”
Recent weak economic data has almost wiped out any expectations that the Bank of England might raise interest rates at its next policy meeting on Thursday.
Official figures recently showed UK GDP grew by just 0.1% in the first quarter.
On Tuesday, figures from lender Halifax pointed to the biggest month-on-month fall in house prices since 2010.