Nearly half of India's coal-fired power stations only have enough stocks to last a week, as the country struggles to meet growing seasonal demand for electricity, the power minister said Thursday.
Piyush Goyal told parliament that demand for power had outstripped supply nationally during the peak summer months between April and June.
Some 46 of 100 coal-fired plants were left with stocks for less than seven days, and measures were being taken to avert a crisis, he said.
Separately, the country's largest power producer, state-run NTPC, warned that six of its plants have stocks for up to just two days of output, and it cannot weather even a "small" disruption in supplies.
NTPC warned of the problem at the plants, which account for 15 percent of India's total energy capacity, in a letter to the power ministry on July 14, according to the Press Trust of India (PTI) news agency.   
"With the ensuing monsoon, it will become more difficult to replenish the coal stocks and in case of even a small disruption, the total power generation at these stations will be adversely affected," NTPC chairman and managing director Arup Roy Choudhury wrote in the letter.
Goyal said the government was taking "corrective" action to improve supplies for power stations, including efforts by state-run giant Coal India to raise production beyond this year's current targets.
"We are increasing the (coal) crushing capacity, increasing (the number of) washeries in mining areas," PTI reported, referring to the facilities where coal is washed as part of processing after it is mined.
"We have also appealed to the environment ministry to allow us to mine additional fuel wherever there are possibilities," he said.
India uses coal to generate more than half of its electricity, and is the world's third-largest importer despite sitting on large reserves, mainly as a result of bureaucratic delays in opening new mines and failure to improve road and rail links to transport coal from remote extraction sites.
Blackouts are common across the country, often triggering protests, as India suffers from poorly maintained transmission lines and overloaded electricity grids.
Prime Minister Narendra Modi's new government, which came to power in May, has pledged to improve power supplies as part of reforms for businesses to help kickstart the ailing economy.
The New Delhi government last month cut power at shopping malls, turned off street lights and announced a string of other emergency measures to conserve power as the mercury soared.
An embarrassing power crisis blacked out half the country two years ago and left more than 600 million people without electricity.
The two days of massive outages in 2012 were blamed on energy-hungry Indian states drawing power from the grids beyond their allocated limits.