MADRID, Sept 2 - The Spanish economy grew by 0.7 percent in the second quarter of 2003 compared with the previous quarter for a year-on-year rise of 2.3 percent, the National Statistics Institute (INE) said on Tuesday. That compared with GDP (gross domestic product) growth of 0.5 percent quarter-on-quarter in the first quarter of 2003 when the economy was growing at an annual rate of 2.1 percent. A poll of 12 economists showed an average forecast of 0.6 percent growth quarter-on-quarter and 2.2 percent year-on-year. The Bank of Spain previously had given its estimate of year-on-year growth for the quarter at 2.2 percent.//