Britain\'s retail sales volumes increased 2.1 percent year on year in August, but dropped 0.9 percent on monthly bases following a strong growth of 1.1 percent in July, said the Office for National Statistics (ONS) on Thursday. The ONS said the main source to drive up the year-on-year growth in the retail sales in August came from the non-store retailing sector, which includes online sales, and sales through mail order, or via stalls and markets. According to the ONS figures, average weekly spending online in August 2013 was 579.6 million pounds (927 million U.S. dollars), an increase of 22.5 percent compared with the same period of last year. The amount spent online accounted for 9.7 percent of all retail spending excluding automotive fuel, said the ONS. However, the ONS attributed the exception year-on-year growth in August to the unusual low retail sales, which were hit by the Olympics and Paralympics as consumers watched the various sports games at the time. A new report issued by the British Retail Consortium (BRC) also showed a drop of 0.9 percent in footfall in shops in August compared with last year, which is the lowest footfall rate since March 2013, but BRC was still optimistic about the outlook. \"A slight fall in shopper numbers is disappointing after several months of positive results, but there are a few factors at play,\" said BRC general Helen Dickinson. \"A small dip in one month shouldn\'t take the shine off the tentative signs of improving consumer confidence hinted at in recent times, and retailers are working hard to read these conditions so that they can continue to deliver for their customers,\" said Dickinson. British retail sector generates 5 percent of the GDP in Britain, with sales exceeding 311 billion pounds in 2012.