There was a sharp fall in power output on Thursday from a plant in Gujarat that left India more than 9,000 megawatts short of peak demand, according to two officials at the state grid operator.
Any grid collapse would cast doubt on the crisis management skills of the new government led by Prime Minister Narendra Modi, whose achievement in ensuring 24-hour power supplies as premier of Gujarat helped him to election victory in May.
Commenting on Thursday, Power and Coal Minister Piyush Goyal said: "I don't know about the possibility of a breakdown ... There is a problem, I think, with many of the coal supplies."
The shortage has come about as a fall in hydroelectricty generation due to weak monsoon rains forced the government to ask coal-based power stations to raise output, an industry source said.
India suffered unprecedented power cuts on July 30-31, 2012, that affected 620 million people -- nearly a tenth of the world's population - in 22 states across the north and east of the country.
Asia's third-largest economy relies on coal to generate more than two-thirds of its electricity, but power plants are running short because state behemoth Coal India Ltd has been unable to meet rising demand.
Cautious steps to open up coal mining to competition have been thrown into chaos by a Supreme Court ruling this week that all coal block allocations since 1993 were illegal. These went to steel, cement and power firms that had to use the coal themselves.
In a second ruling next Monday, the court will decide whether to scrap the awards of more than 200 of these 'captive' blocks, or instead fine licence holders, promising further uncertainty before new mines can ramp up output.
The Indian Express reported on Friday that 10 out of 13 thermal plants that have suffered forced outages are state-run, raising questions over exactly how Coal India allocates supplies. A Coal India spokesman had no immediate comment.
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