Growth of key infrastructure industries has slowed down to 2.3 per cent in September this year from 3.3 per cent a year ago. According to the data released by the Finance Ministry today, the cumulative growth rate from April to September this fiscal stood at 4.9 percent as against 5.6 percent during the corresponding period last fiscal.The eight core industries have a combined weight of over 37 per cent in the Index of Industrial Production, IIP, and consists of Coal, Crude Oil, Natural Gas, Petroleum Refinery products, Fertilizers, Steel, Cement and Electricity. The decline in the index is mainly due to the poor performance in the production of coal, crude oil and natural gas. While the coal sector registered a negative growth of 17.8 percent this September, natural gas production declined from 12.6 percent last year to minus 6.4 percent. However Petroleum Refinery Production and electricity generation registered an impressive growth. Petroleum Refinery generation grew from minus 10.2 percent last September to a positive growth rate of over four percent this year. The index of electricity generation stood at nearly nine percent in September this year as against two percent a year ago.