Calcutta, May 30: The government has issued caution notices to 25 medium and heavy industries across Bengal over the past few months on charges of polluting the environment.

Industries that have deposited earnest money with the state pollution control board over the past one year will have to forfeit the amount of Rs 50 lakh as a result.

The PCB has now given the errant industries three months’ time to set up waste-treatment plants to avoid closure.

The blacklisted industries include two public sector undertakings, Durgapur Steel Plant and the Indian Oil Corporation at Haldia.

PCB officials said the factories have been discharging effluents into rivers and lakes without treating them.

“As per the environment protection act, it is mandatory for all industries to set up effluent treatment plants so that no chemical and other hazardous particular can flow into rivers. Besides, steps must be taken to prevent emission of black smoke from chimneys. We are initiating stern action against the industries as they have flouted rules despite several reminders,” PCB member-secretary Shyamal Sarkar said yesterday.

All industries have to deposit money with the PCB in the form of bank guarantees with an assurance that effluent or solid waste-treatment plants would be set up according to the norms, he said.

The amount stands forfeited if the authorities fail to do so.

Senior PCB officials said they would carry out extensive and regular inspection of all major polluting units to see if they are following the norms. “We will take stern action if any unit is found violating the rules,’’ an official said.

The authorities of large and medium industries will be asked to attend a meeting called by the PCB to make them aware of the rules.

“Many units have already changed the fuel in a bid to reduce air pollution and work is in progress in some units. We have made it clear to all concerned that not a single polluting industry will be allowed to operate in the state,’’ PCB’s member-secretary said.