New Delhi - India's biggest power producer, NTPC plans to buy more coal from private mining companies to overcome fuel shortages and meet rising electricity demand, two people familiar with the matter said.

India is relying on thermal power to meet rising demand triggered by an extended summer and weaker hydropower generation linked to an El Niño weather pattern, government data showed.

Its power deficit rose to more than a three-year high in September despite coal-fired plants operating at a higher rate.

NTPC, which did not respond to a Reuters request for comment, typically buys fuel from State-run Coal India, the world's largest coal producer.

The utility's coal reserves at its plants have dropped from 18-million metric tons in April to 5.5-million tons as higher power generation and weaker local supplies due to heavy rains in mining areas have constrained replenishment, the people said.

NTPC is in talks with private companies to buy up to 15-million tons of coal and plans to use about 50-million tons produced from its captive mine, they added.

If the coal supplies are not ramped up, NTPC anticipates a severe power shortage early next year, the people said.

NTPC's coal consumption is expected to rise in 2026/27 to nearly 300-million tons from an average of 270-million to 280-million tons as it increases operations to meet rising electricity demand.

Nearly 47% of India's power plants had critically low levels of coal stocks, with supplies sufficient to generate power for less than four days at those plants.

To overcome power shortages, the federal power ministry last week asked more than 100 captive coal-fired power plants ​to operate at maximum capacity from October 1 through ‌year-end.

India is considering mandatory imported coal blending at power plants due to local shortages, Reuters reported last month.

Meanwhile, India's federal coal ministry said on Monday that Coal India has ramped up supplies to Indian power plants after rains in mining areas.

Coal remains central to India's power system even as the country expands renewable energy to reduce its reliance on fossil fuels and curb carbon emissions.