Bulgaria's ruling centrist-right GERB party will back the opposition proposed referendum on the fate of the Belene Nuclear Power project, even though it deems it anti-constitutional, Bulgarian Prime Minister Boyko Borisov has said.

"If we don't support it, people will say we are against democracy and that we don't want to hear the voice of the people," Borisov explained on Friday, adding that the referendum may end up canceled by the Constitutional Court.

The Prime Minister told reporters that the way the left-wing Bulgarian Socialist Party posed the question to people while gathering signatures for the referendum was "anti-constitutional and manipulative."

As the right-wing oppositional Blue Coalition has pointed out on several occasions, the referendum may be declared anti-constitutional, since the Bulgarian Constitution does not allow referendums to be scheduled on the country's financial and budget issues.

Borisov's GERB government scrapped the Belene NPP project in March 2012, declaring it economically unfeasible. The pro-Belene BSP then launched a petition for a referendum on the Russian-Bulgarian project's fate.

The inspection of the petition recently concluded, with 543 639 valid signatures, enough to make the vote irreversible.

The referendum is expected to take place within the next three months.