India's coal imports from Australia and Colombia will increase in the long run as demand for high-energy coal grows due to environmental reasons, Dale Hazelton said at the India Coal Conference in New Delhi.

Coal is among the top five commodities imported by India, one of the world's largest consumers of coal, and its imports of the dirty fuel rose in 2018 after two consecutive years of decline.

WoodMac previously said India's thermal coal imports grew at their fastest pace since 2014 to 164 million tonnes in 2018.

Hazelton said he expects coal imports from the United States to remain volatile "in line with movement of prices of petcoke".

India's imports of American coal grew 24% in 2018-19 largely due to restrictions on consumption of petroleum coke, a better burning alternative to coal, in some parts of the country.

The energy hungry nation's overall coal demand rose 9.1% to 991.35 million tonnes during the year ended March 2019, with  utilities accounting for a lion's share of the consumption.

Consumption by state-run NTPC Ltd, India's largest electricity generator, was 185 million tonnes in 2018-19, Prakash Tewari, the company's director of operations, said on Tuesday. This accounted for about a fourth of total demand from Indian utilities.

Imports have been rising mainly because of state-run Coal India's inability to cater to demand from the cement and sponge iron industries, whose coal requirements rose by over two-thirds during 2018-19.

Indonesia remained the top supplier of thermal coal in 2018-19, accounting for three-fifths, or 111.6 million tonnes, according to government data.

Imports from South Africa amounted to 31.15 million tonnes, or less than a sixth of total thermal coal imports. Imports of thermal coal from the United States rose by 24% to 10.84 million tonnes, the largest gain by a country in percentage terms.