The growth in production of eight key infrastructure sectors slowed down to 6.1 per cent in July this year due to a decline in the output of crude oil and natural gas, according to official data released on Friday. The growth rate, however, is up from 5.1 per cent in June. The growth of core sectors -- coal, crude oil, natural gas, refinery products, fertiliser, steel, cement and electricity -- was 8.5 per cent in July 2023. During April-July this fiscal, the output of core sectors rose by 6.1 per cent against 6.6 per cent in the same period last fiscal. The eight core sectors contribute 40.27 per cent to the Index of Industrial Production (IIP) which measures overall industrial growth. Crude oil and natural gas output contracted by (-) 2.9 per cent and (-) 1.3 per cent, respectively, in July.