Eight core industrial sectors grew 5.2% year-on-year in September, the highest in six months, government data showed on Tuesday. The index of eight core sectors includes coal, crude oil, natural gas, refinery products, fertilisers, steel, cement and electricity.

The cumulative growth in the index during April-September was 3.3%, according to data from the Ministry of Commerce and Industry. The growth in the overall index was the highest since April, when it had rise 2.6%.

The highest growth during September was seen in coal, refinery products and natural gas. Coal grew 10.6%, refinery products 8.1% and natural gas 6.3% in the month.

The fertiliser sector was the only one to show a decline, of 7.7%, while the crude oil industry rose 0.1%.

The eight core industries account for about 40% weight in the calculation of the Index of Industrial Production. The Index of Industrial Production grew 4.3% in August, after rising only 0.9% in July. The index is an indicator of the state of various industrial sectors in the economy.