Growth of eight core sectors slipped to 3.6 percent in June against 5.6 percent in the same month last year, according to official figures released Wednesday.

"The core sector numbers are very poor. It will have its effect on IIP as well," Principal Economist D K Joshi said.

The eight industries include crude oil, petroleum refinery products, coal, electricity, cement and finished steel and have a weight of 37.9 percent in the overall Index of Industrial Production (IIP).

Natural gas and crude oil production contracted by 11.1 percent and 0.8 percent respectively during June.

Steel and fertiliser production shrunk by 0.5 percent and 11.7 percent respectively during the month.

However, coal and petroleum refinery output grew by 7.2 percent, 10.2 percent and 6.1 percent respectively.

Cement production registered a growth of 10.2% in June 2012 against its 1.7% growth in June 2011.

Core sector growth in May too moderated to 4 percent, from 5.9 percent in the same month last year.

Hit hard by global woes and domestic problems, India's economic growth rate slowed to nine-year low, both in the March quarter at 5.3 percent, as well as for the 2011-12 fiscal at 6.5 percent, prompting the industry to demand immediate and bold action to arrest slowdown.