PES and opposition Bulgarian Socialist Party chair Sergey Stanishev and Bulgarian PM Boyko Borisov have accused each other of inconsistencies in their position regarding the Belene NPP.
Sunday Borisov stated that he will instruct members of ruling GERB party to vote "no" at a national referendum on nuclear energy January 27.
The question posed to Bulgarian citizens will be "Should nuclear energy be developed in Bulgaria through the construction of new nuclear power units?"
The specific cause for the convocation of a referendum is the unclear fate of frozen Belene NPP project.
The referendum was sponsored by the Bulgarian Socialist Party, which gathered a petition of more than the 0.5 M legally needed signatures.
Later Sunday BSP chair Stanishev issued a statement criticizing Borisov for his "U-turn" on the case, recalling that in past weeks the PM had favored a positive vote.
"The classic definition of a U-turn is to unveil the start of construction for Belene NPP at three ceremonies, and to still fail to sign the contract for the construction," retorted Borisov.
He was refering to Stanishev's term in office as Bulgaria's previous PM, 2005-9.
In the interview Sunday, Borisov had uncharacteristically praised Stanishev for not signing the Belene NPP project, allegedly because seeing it is economically ineffective.