Bulgaria's Prime Minister should explain why no government official was present at the energy meeting held by ministers of Eastern European countries, the opposition believes.

Tuesday's event in Hungarian capital Budapest included ministers from Serbia, Greece, Macedonia, Turkey, and Hungary, who agreed to boost energy cooperation in the name of the "welfare of the citizens", according to their joint declaration.

Later the participants also announced they were ready and willing to enter the "Turkish Stream" gas pipeline project, an alternative to South Stream after Russia dropped the latter in December of last year.

According Yanaki Stoilov, a key member of the Bulgarian Socialist Party (BSP), the absence of a Bulgarian representative is not a good sign.

He said in Parliament on Wednesday that Borisov should give his account from the rostrum and say what role would Bulgaria take in the project.

Russia argues South Stream, which would have transported 63 billion cubic meters of gas, could not be carried out due to Bulgaria's reluctance to provide construction permits.

Neighboring states and all countries that were parties to the project declared last year they would seek their inclusion in the new "Turkish Stream" project.