Reflecting a slowdown, the growth of eight core sectors slipped to 3.6 per cent in June, weighed down by contraction in natural gas, fertiliser and steel output.
The key infrastructure sectors had grown 5.6 per cent in the same month last year.
The growth in May too moderated to 4 per cent, from 5.9 per cent in the same month last year.
The cumulative expansion of these industries in April-June 2012 slowed to 3.6 per cent from 5.2 per cent in the same period last year, according to official data released on Wednesday.
The eight industries include crude oil, petroleum refinery products, coal, electricity, cement and finished steel and have a weight of 37.9 per cent in the overall Index of Industrial Production (IIP).
Economists said the poor performance of core industries clearly points to economic slowdown. These numbers will have implications on industrial production data for June to be released later this month.
"The core sector numbers are very poor. It will have its effect on IIP as well," Principal Economist D K Joshi said.
Natural gas and crude oil production contracted by 11.1 per cent and 0.8 per cent respectively during June.
Steel and fertiliser production shrunk by 0.5 per cent and 11.7 per cent respectively during the month.
However, coal, cement and petroleum refinery output grew by 7.2 per cent, 10.2 per cent and 6.1 per cent respectively.