The output growth of eight core sector industries slowed to 2.1 per cent in December 2013 due to a poor showing by coal, petroleum refinery products, steel and cement sectors.

The eight core sector industries -- coal, crude oil, natural gas, refinery products, fertilisers, steel, cement, electricity -- grew by 7.5 per cent in December 2012.

According to the data released by the government today, the output of eight infrastructure industries in April- December 2013 grew by a mere 2.5 per cent against 6.8 per cent in the same period of the previous fiscal.

The eight core industries have a combined weight of about 38 per cent in the Index for Industrial Production (IIP).

The December IIP numbers would be released in the second week of January.

Coal output fell (-) 0.6 per cent in December year-on- year. Petroleum refinery production shrank by (-) 1.7 per cent.

Steel output growth slowed down to 3.1 per cent in the month under review. Cement production also decelerated by 1.1 per cent.

Among those which put up a good performance, crude oil which registered a growth of 1.6 per cent and electricity generation grew at 6.7 per cent.

Natural gas output was in negative zone (-) 9.9 per cent in December as against (-) 14.9 per cent in December 2012.