Bulgaria's Energy Ministry has sent a formal letter to state-owned Russian company Rosatom, inviting experts from the energy giant to the country, the ministry's press office says.

Minister Temenuzhka Petkova has cited the need to set up the parameters and composition of a working froup on the Belene nuclear power plant (NPP) project.

The move to form the working group was agreed by Bulgarian Prime Minister Boyko Borisov and Russian President Vladimir Putin last week.

Their phone conversation came after more than a year of tensions between Bulgaria and Russia with regard to energy affairs that followed the cancellation of three major joint energy projects involving the two countries in just a few years.

Prior to talks, a letter was submitted to Sofia by EU Commission President Jean-Claude Juncker that hinted at a possible revival of the Belene NPP project.

Borisov, whose previous government had brought the project to a halt, said in June the current one did not rule out a restart anymore, with Bulgaria being forced to buy reactors and nuclear equipment from Atomstroyexport (Rosatom's export arm) under an arbitration ruling.

The meeting of Bulgarian and Russian experts should take place between August 15 and 30, Minister Petkova has said.