Retail sales rose 0.3 percent in July after a gain of 0.8 percent in June, boosted by petrol promotions and high levels of discounting, the Office for National Statistics said Thursday. Market expectations had been for a flat reading, according to analysts polled by Dow Jones Newswires, while the ONS revised upward July\'s level after an initial gain of 0.1 percent. Sales in July meanwhile surged by 2.8 percent compared with the same period a year earlier, exceeding forecasts for a rise of 1.6 percent. The July trading period covered two days of the London 2012 Olympics -- July 27 and 28 -- but the ONS added that feedback from retailers suggests there was no impact on sales.