Retail sales fell by a worse than expected 1.8% last month as price increases started to bite, official figures show.
The month-on-month decline in sales volumes was much bigger than the 0.2% slip expected by economists and comes as consumers face a squeeze from accelerating inflation.
Figures from the Office for National Statistics (ONS) also showed a 1.4% decline over the first three months of the year - the first quarterly fall since 2013 and the biggest since 2010.
At the same time average store prices were up 3.3% compared to the same period last year, the largest growth since March 2012 - led by petrol stations.
Kate Davies, ONS senior statistician, said the decline "seems to be a consequence of price increases across a whole range of sectors".
It follows separate official figures last month that showed wage growth had slipped down to the rate of inflation, meaning the real terms value of pay for households is not going up.
Prices are being pushed higher by the weakness of the pound - which has fallen sharply since the Brexit vote, driving up the cost of imports purchased in foreign currencies.
The squeeze on household spending power threatens to derail the strong consumer activity that has helped keep the economy on course since the referendum.
Scotiabank economist Alan Clarke said the latest retail sales figures added to evidence that official UK growth figures published next week will show a marked slowdown.
He added that any Bank of England officials who might have been considering an interest rate rise would be more hesitant now.
Simon Wells, chief European economist at HSBC, said consumers were "feeling the pinch".
He added: "As UK inflation continues to climb, but with wage growth still sluggish, we expect this trend of weaker retail activity to continue over the coming months."