Finnish utility TVO claimed partial victory Thursday in a bitter dispute with France's Areva over a troubled nuclear reactor in International Chamber of Commerce arbitration, but the French side dismissed the ruling as "technical".

Areva, together with German engineering group Siemens, has been building in Finland since 2005 what was meant to be a showcase of French-German know-how but delays and cost overruns turned the project into a fight with their Finnish client TVO at the ICC.

On Thursday, the ICC gave a partial ruling in the dispute, without however taking a position on the monetary claims of the companies.

A spokesperson for the French nuclear giant told AFP the decision was "technical" and that Areva remains "confident" ahead of the final outcome, which it expects to come at the end of 2017 or beginning of 2018.

But Areva's Finnish client TVO saw things differently.

"The partial award has finally resolved the great majority of these facts and matters in favour of TVO, and conversely has rejected the great majority of the supplier's contentions," it said, referring to "time schedule, licensing and licensability, and system design" in the early period of the construction.

The core issue of financial liabilities remains unsolved, with Areva claiming damages of 3.4 billion euros ($3.7 billion), and TVO 2.6 billion euros.

"The hearings are not over, they are to continue," Areva said.

The Olkiluoto 3 reactor in western Finland was supposed to be the world's first European Pressurised Reactor (EPR), with a start date initially planned in 2009 but now delayed to 2018.

But now another EPR, in China, looks set to beat that target, starting production in 2017, despite construction work starting later than in Finland.

Parallel to the arbitration, the adversaries were negotiating directly with each other to settle the dispute but talks were called off in May and have not resumed since.

French electricity giant EDF is seeking to take over Areva's reactor business but does not want exposure to the financial risks associated with the Finnish reactor, originally sold to TVO as a turnkey project.

In September, TVO took fresh legal action against Areva in a French commercial court to seek assurances that the Olkiluoto 3 project would not get delayed again.

Areva has promised that it won't, saying the plant's cold tests, without nuclear fuel, are due to begin in 2017.