Over 20 heavily armed ultras attacked the unit run by Orissa Hydro Power Corporation (OHPC), about 60 km from here, set afire some portions of the plant and overpowered those on duty last night, Superintendent of Police Satyabrata Bhoi said.

After tying about six persons to a structure outside the power house, the Maoists ransacked the valve house atop a hill and set fire to equipment, causing extensive damage to some machines, Bhoi said.

In a simultaneous attack, the ultras also damaged the intake tunnel through which water was flowing inside, crippling power generation at the unit, he said.

The red rebels put up several posters and banners carrying messages against the government and police before disappearing into the nearby dense forest, the police said.
Local residents said that the Maoists triggered explosions damaging machines and some vital structures in the power house.

Meanwhile, additional security forces were rushed to the site and a massive combing operation was launched to track the ultras, they said.

Senior engineers and experts have rushed to the plant to take steps for resumption of power generation, official sources said, adding that the project with a total capacity of 510 mw, was generating about 360 mw at present in view of low water level.