UK retailers saw sales fall in March, led by declining sales at petrol stations, according to the Office for National Statistics (ONS).
Petrol sales fell 6.2% in March compared to the previous month, causing overall sales to fall by 0.5%.
The UK pound slipped below $1.50 on the back of the news, which has raised questions over the extent of economic growth in the UK for 2015. Many analysts had expected an increase in the region of 0.4%.
If petrol figures were taken out of the figures, overall sales would have risen 0.2% in March.
Over the first three months of 2015, sales rose 0.9%, down from 2.2% in the first quarter of the previous year.
Howard Archer, chief UK and European economist at IHS Global Insight, predicted overall economic growth would reach 0.5% for the first quarter.
He said: "Concern that GDP growth could have slowed appreciably in the first quarter of 2015 has been fuelled by disappointing industrial production and [especially] construction output data for February as well as weaker trade data."