An Areva-Siemens consortium and TVO are seeking billions of euros from one another over delays and cost overruns on the reactor originally planned to start operating in 2009 but now expected to open in 2018.

"We believed that we were close to solutions, but the French side broke off the talks," TVO spokeswoman Anna Lehtiranta said.

The dispute is blocking a planned takeover of Areva's nuclear reactor division by another state-controlled utility EDF, which does not does not want to take on any Olkiluoto-related liabilities.

TVO's Lehtiranta said the Finnish company was ready to accept a proposed deal whereby the Olkiluoto contract would have been moved outside EDF and Areva would have paid TVO for the delays.

The Finnish company is hitting back at French media reports this week, which said TVO had blocked the contract transfer.

"We are not to blame, we are ready to continue the talks," Lehtiranta said.

TVO says the reactor delay is a result of insufficient planning and execution by the supplier, while Areva argues that TVO's inflexibility has been partly to blame.

When the project was launched, its cost was estimated at 3.2 billion euros (2.4 billion pounds), but in 2012 Areva estimated the overall cost would end up closer to 8.5 billion euros.

TVO's owners include Finnish paper companies UPM and Stora Enso and utility Fortum.

(Reporting by Jussi Rosendahl; Editing by David Goodman)

Stocks treated in this article : EDF, Siemens AG, Stora Enso OYJ, Fortum Oyj, UPM-Kymmene Corporation, Areva