British retail sales fell by 0.3% in January despite a boost from motorists taking advantage of cheaper petrol by filling up their cars much more.
Sales volumes excluding fuel were even worse, falling by 0.7%, according to the Office for National Statistics.
Average prices fell by 3.1% in January compared with the same month the year before, the largest year-on-year fall since records began in 1997.
It was driven by a 15.1% fall in petrol stations as world oil prices tumbled.
The ONS said there was a significant increase in volumes bought at filling stations as well as department stores but there was downward pressure from supermarkets as well as fashion shops.
Motorists pumped 11.1% more fuel into their cars compared to the same month last year while month-on-month volumes were up 3%.
In supermarkets, volumes were down 0.9% on the month while clothing and footwear shops were down 0.4%, but department stores grew by 2.7%.
Retail sales in January were up 5.4% compared with the same month last year while the underlying pattern of three-month-on-three-month showed growth of 2.3%, the strongest since April 2002.
Figures showed the amount spent in January was 1% lower than in December but 2.3% higher than January 2014.
The average weekly spend in the retail industry last month was #6.5 billion, compared with £6.3bn in the same month last year and £9bn in December 2014.
The value of internet sales decreased by 0.2% month-on-month in January but were up 12% on January 2014.
James Knightley of ING Bank said the figures showed a "mixed performance for retailers".
He added that the year-on-year rise of 11.1% in fuel store volumes was "quite remarkable" since demand for petrol was not normally thought to be affected by price.
"There has been some anecdotal evidence that drivers are topping up their cars more frequently, perhaps because they don't feel the cheap prices will last and this data seems to support that assumption.
"In terms of the outlooks for consumer spending, we remain optimistic given rising real incomes and employment while the impending increase in the tax-free personal allowance will also put more money in people's pockets.
"Consumer confidence is already back to pre-crisis highs so it looks as though GDP growth will be consumer-led in 2015."
