Bulgaria's Parliament should not come up with a decision to launch negotiations with a private investor for the abandoned Belene Nuclear Power Plant project before the plant's fate is decided in a referendum, Bulgarian President Rosen Plevneliev has declared.

Plevneliev said he was in favor of the referendum taking place by April 2013, separately from the general elections scheduled for next year's summer.

"We have over 500 000 valid signatures calling for a nationwide vote, therefore the referendum must take place. Otherwise, we will be harming democracy," the President from the ruling centrist-right GERB told reporters on Monday.

In the light of the upcoming referendum, negotiations should not be started in Parliament with the recently emerged investment fund, Plevneliev stated, adding that the fund was not a strategic investor.

Last week, the recently US-registered Global Power Consortium expressed interest in taking over the project to install two 1,000 megawatt nuclear reactors at the Danube River town of Belene and build it without state funds or guarantees.

The companies behind the consortium are yet unknown.

The consortium brings together the US investment fund Quantum Group, two large strategic investors, a big US bank and one operator, according to Bogomil Manchev, owner of "Risk Engineering" company and consultant for the alleged US investors for the project.

The Bulgarian government scrapped the Belene NPP project earlier in 2012, declaring it economically unfeasible. The pro-Belene Bulgarian Socialist Party then launched a petition for a referendum on the project's fate.

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