The decision was made unanimously by councillors from Labin, Rasa, Sveta Nedelja, Pican and Krasan at their meetings on Monday, Labin mayor Tulio Demetlika told Hina on Tuesday.
The question on the referendum ballot paper will be: "Are you in favour of the construction of the Plomin C coal-fired thermal power plant?"
Councillors said that the local population had so far always been excluded from decisions on strategic national projects in their region.
Demetlika called on the people of the Labin region to turn out for the vote in large numbers.