ONS said retail volumes rose 2.1 percent from August 2012. Economists had expected a gain of more than 3 percent.
Despite falling short of expectations, the month continues a pattern of growth that began in April, ONS said.
The largest growth segment for the month was in non-store retail, which is the term given to online and catalog sales.
Gains were made in part due to artificially depressed figures from August 2012 when shoppers were busy watching the Olympics, ONS said.
Negative pressure in the month came from the food sector, where sales by volume fell 2.7 percent. That too, reflected skewed data, ONS said, due to a spike in the sector in July when a heatwave prompted high volumes of beverage sales.
Inflation in the retail sector fell from an annual rate of 1.8 percent in July to 1.6 percent in August. The largest price gains were in motor grade gasoline, where prices rose 1.5 percent after rising 2.6 percent in July.
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