The production of crude oil declined by 0.5 per cent, refinery products by 2.7 per cent, fertiliser by 0.3 per cent and cement by 2 per cent, as per official data.
Coal output growth decelerated to 0.7 per cent last month as against 4.1 per cent in July 2016.
According to data, natural gas output rose by 6.6 per cent in July.
Steel production and power generation rose to 9.2 per cent and 5.4 per cent, respectively in July this year from zero per cent and 2.1 per cent in the same month last year.
Cumulatively, the eight core sectors in April-July recorded a growth of 2.5 per cent as against 6 per cent in the same period a year ago.
Slow growth in key sectors would also have implications on the Index of Industrial Production (IIP) as these segments account for about 41 per cent to the total factory output.
In June, these eight sectors had recorded a growth rate of 0.8 per cent.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)