Bulgaria's state-run power grid operator NEK and Russia's state nuclear company Atomstroyexport have set up a financial working group on the Balkan country's planned Belene nuclear plant, it emerged on Friday.

The financial group has been set up under the provisions of Appendix 13 to the agreement for the construction of Belene nuclear power plant, signed by NEK and Atomstroyexport, which was contracted to build two 1,000 megawatt reactors at the Danube town.

Representatives of Atomstroyexport have agreed with the Bulgarian side and formally submitted to the Minister of Economy and Energy Traicho Traikov a roadmap, which maps out the most important steps to implement the project for the construction of Belene plant, Moscow announced.

No further details about the roadmap were immediately available.

The news comes days after Bulgaria's National Electricity Transmission Company NEK threatened to sue in Geneva Russia's state nuclear company Atomstroyexport over delayed payments on planned Belene nuclear plant.

The government in Sofia however was quick to point out that this is not a counter-claim to Moscow's lawsuit at an arbitration court in Paris, which is again on due payments on the nuclear project.

"The action was described as a "counter claim" just because the two sums in question are similar," a statement by the Economy and Energy Ministry said.

It was not immediately clear however why the Bulgarian authorities have picked the Swiss town for their lawsuit.

Meanwhile it emerged that Bulgaria and Russia will discuss possibilities for Russia's Atomstroyexport to withdraw its EUR 58 M claim at the negotiation table.

Bulgaria's National Electricity Transmission Company NEK has received a letter by Atomstroyexport to this effect on Tuesday. According to Minister Traikov negotiations will continue until August 12 at the latest.

Two weeks ago Russia's state nuclear company Atomstroyexport took Bulgaria's NEK to an arbitration court for EUR 58 M over delayed payments for its work on two nuclear reactors.

The next day the Bulgarian company said it is ready to strike back with a EUR 61 M counter claim against Atomstroyexport over delayed payments for purchases of old equipment for the plant, worth about EUR 300 M.

Minister Traikov explained on Sunday that the Bulgarian side has offered Moscow a few options on how to settle the scores without resorting to the arbitration court.

"One of the proposals they received suggests that instead of being involved in court battles, the two companies settle the claims by offsetting," said Traikov, but added that the Bulgarian company is ready to lodge a counter-claim should Russia perseveres.

In the middle of June Bulgaria said that Belene nuclear project will be frozen for another three months as of July to have time to catch up with the back office work and get more information about the cost of the project.

Bulgaria and Russia have been unable to agree on the major bone of contention - the price for the construction of the 2000-MW Belene NPP.

Russia says the project construction price should be EUR 6.3 B. The Borisov government wants to set the price at as little as EUR 5 B.

After it was first started in the 1980s, the construction of Bulgaria's second nuclear power plant at Belene on the Danube was stopped in the early 1990s over lack of money and environmental protests.

After selecting the Russian company Atomstroyexport, a subsidiary of Rosatom, to build a two 1000-MW reactors at Belene and signing a deal for the construction, allegedly for the price of EUR 3.997 B, with the Russians during Putin's visit to Sofia in January 2008, in September 2008, former Prime Minister Stanishev gave a formal restart of the building of Belene. At the end of 2008, German energy giant RWE was selected as a strategic foreign investor for the plant.

The Belene NPP has been de facto frozen since the fall of 2009 when the previously selected strategic investor, the German company RWE, which was supposed to provide EUR 2 B in exchange for a 49% stake, pulled out.