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Economists polled by Reuters had expected a 0.1 percent monthly and a 0.5 percent annual increase after sales contracted 0.4 percent month-on-month in July and rose 0.5 percent on the year.
Though volatile, retail sales data is a proxy for household demand, one of the weaker elements of the euro zone recovery that stalled in the second quarter.
Eurostat data showed sales of non-food products, and fuel at petrol stations made the biggest contribution to the monthly rise of the index in August, with the euro zone's biggest economy Germany reporting the biggest gain of 2.5 percent.
In annual terms, sales of non-food products played an even bigger role as their 3.6 percent year-on-year rise offset a 0.2 percent fall in the sales of food and the same drop in the sales of petrol.
Both Germany and second biggest France recorded strong gains of 3.1 and 2.1 percent respectively.
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