Retail sales growth may have been at its strongest in more than three years this August, a survey by the Confederation of British Industry (CBI) suggested today. Its monthly survey of retailers showed the sales balance rising unexpectedly this month to 35 from 33 in July, marking the highest reading since April 2007. City economists had expected the balance to fall to 20. Lai Wah Co, head of economic analysis at the CBI, said: "Better sales growth continued in the high street in early August, and retailers are upbeat about prospects in the coming three months. "The summer sales, some warmer weather and the school holidays will no doubt have helped, lifting sales of clothing and shoes, and encouraging households to invest in some home improvements." The CBI's quarterly survey showed an even stronger performance, with the rise in the retail business situation balance to 22 from 5 in May, giving the highest reading since May 2004.