It was the third such incident in the district in a year, the official said.
Five villagers and a worker at the site owned by Reliance Power were swept up in a flow of fly ash which travelled at least six kilometres, swallowing up whole agricultural fields along the way.
Fly ash is a powdery byproduct of burning pulverised coal.
“The sludge flowed from the dyke and then mixed with a stream, which carried it further,” said K.V.S. Chaudhary, the top local official in the Singrauli district.
The 4,000 megawatt (MW) plant was running at full capacity and was not expected to shut, he said.
It was not clear how the dyke broke and Reliance Power said it was investigating the causes of the incident, adding the plant would continue to operate normally independent of relief operations.
Local media reported a fly ash dyke break at a plant operated by Essar in August and another run by NTPC Ltd in October.