New Delhi, Jan. 31 -- India's infrastructure output, which accounts for about two-fifths of industrial production, slowed in December compared to the previous month, as production of four of the eight core constituent sectors, coal, natural gas, refinery products, and fertilisers, fell during the month.

The index of the eight core industries fell to 4% annually in December after registering a 4.4% growth in November and 3.7% in October, according to provisional data released by the Ministry of Commerce and Industry on Friday.

It had expanded by 2.4% in September and contracted by 1.5% in August.

A year ago, the output of the eight core industries-coal, crude oil, steel, cement, electricity, fertilisers, refinery products and natural ga...