During March, the core sector data showed a marginal deceleration to 2.9 per cent from 3 per cent in the same month of the previous fiscal.
For the entire 2012-13, the growth rate of eight core sector industries halved to 2.6 per cent from 5 per cent in 2011-12, according to the data released by the Commerce and Industry Ministry today.
The industries - crude oil, petroleum refinery products, natural gas, fertilisers, coal, electricity, cement and finished steel - have a weight of 37.9 per cent in the Index of Industrial Production (IIP).
"The core sectors are weak in India. Manufacturing has slowed down. It will have an impact on IIP. What we need is policy attention," Crisil Chief Economist D K Joshi said.
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"The marginal decline in growth in March was on account of negative growth witnessed in the production of natural gas and low growth recorded in the production of coal and crude oil," the official said.
Production of natural gas contracted by 17.7 per cent in March. Coal output growth dropped to 0.3 per cent from 7.3 per cent in March 2012.