Bulgaria's Deputy Energy Minister Mariy Kosev, who resigned on Wednesday, said his removal was prompted by "a change in the political environment" and the appointment of "a more politicized candidate".

"I have pressed for reforms while I was on the job, defending Bulgaria's national interests all the while", insisted Kosev, who resigned along with Transport Minister Alexander Tsvetkov.

The outgoing Deputy Energy Minister dismissed as "unfounded" claims by GERB MPs that his replacement was connected to the Renewable Energy Act. The controversial piece of legislation drove a rift between the business sector and the government, with allegations that it was too restrictive in nature.

The Belene NPP project, however, could have provoked the reshuffle, Kosev admitted, adding that he could not say that "for sure".

Kosev headed the working group on the financial terms of the project for a 2,000 megawatt nuclear plant on the Danube, in the northern town of Belene.

He was the one to disclose that Lukoil Bulgaria CEO Valentin Zlatev had been present at a meeting with the Russians. Later on, Minister of Economy, Energy and Tourism Traycho Traykov confirmed the statement, making it clear that Zlatev attended the meeting as an advisor to Rosatom.

This happened in the wake of the scandal between Minister Traykov and Zlatev over the cost of fuel in Bulgaria, which ended in a final warning for Traykov from Prime Minister Borisov.

Borisov's U-turn in favor of Belene nuclear plant earlier this year fuelled suspicions that links between the mafia and the political system run deep in the energy sector.

The man believed to be pulling the strings behind the curtains, the back seat ruler, is Valentin Zlatev, CEO of Lukoil Bulgaria. Analysts say it must be by no accident that only after he intervened in the talks for Belene Borisov suddenly changed his mind in favor of the project.