Retail sales fell by a worse-than-expected 0.5% in October, after a mild autumn hit sales of winter clothes.
Sales at household goods stores fell 3% following a particularly strong August and September, the Office for National Statistics (ONS) said.
For the three months to October, retail sales rose 0.4% – a considerable slowdown from the 2.3% increase recorded for the three months to July.
Analysts said October’s fall suggested shoppers were cutting back spending.
Samuel Tombs at Pantheon Macroeconomics said the drop was the “first real sign that consumers are tightening their purse strings due to uncertainty about Brexit”.
Non-food sales fell 1.3%, with a 1% decline fall in clothing sales, which he said could not be blamed on the weather.
“Consumers’ confidence already has weakened in recent months due to concerns about the economic outlook and we doubt households are feeling any surer that a no-deal Brexit will be avoided after this week’s political turbulence,” Mr Tombs said.
“Unless the government miraculously manages to force the current withdrawal agreement through parliament soon, growth in consumers’ spending will weaken markedly in the fourth quarter.”
Thomas Pugh at Capital Economics said some of October’s weakness may reflect consumers delaying spending ahead of “Black Friday” discounts this month.
“High oil prices also weighed on the volume of fuel sold. As such, we suspect that there could be a rebound in sales volumes in November as oil prices have fallen sharply and if Black Friday sales pick up,” he added.