An explosion has occurred near sixth generator at the Moolamattom power station around 12 noon today.
However, no casualty has been reported and the reason for the mishap is yet to be ascertained.
Power generation has been halted following the blast which filled smoke at the underground power plant.
There was an explosion at second generator here a week ago.
The biggest underground hydro-electric Project in India. Moolamattom Power Station is fed by water from the Idukki Dam built across Periyar River.