NEW DELHI, Oct 21 (Reuters) - India's infrastructure output (ININFR=ECI), opens new tab grew at its slowest pace in three months in September, weighed by a decline in coal, natural gas and refinery products.

The index, which tracks activity across eight sectors and makes up 40% of the country's industrial production, grew at 3% year-on-year in September versus a revised 6.5% growth in August. The infrastructure output was 2.2% in June.

KEY NUMBERS

• Crude oil output fell 1.3% year-on-year in September against a revised increase of 2.4% in August.

• Natural gas production declined 3.8% year-on-year in September as compared to a 2.2% fall in the previous month.

• Cement output rose 5.3% year-on-year in September after a revised 5.4% increase in August.

• Steel production rose 14.1% year-on-year in September after a revised increase of 13.6% in August.

• Fertiliser production increased 1.6% year-on-year in September versus 4.6% rise in the previous month.

• Coal production fell 1.2% year-on-year in September as compared to a growth of 11.4% in August.

• Electricity generation increased 2.1% in September year-on-year versus a growth of 4.1% in August.

• Refinery products output fell 3.7% in September year-on-year as compared to a growth of 3% in August.

• Infrastructure output grew 2.9% year-on-year in April-September against a growth of a revised 4.3% a year ago.