The landmark 1,600 MW OL3 EPR reactor has struggled against construction delays and cost overruns. In early June Areva said that the new plant would start operating at the end of 2012, more than three years behind schedule.

Areva, which has blamed the delays on Finnish utility TVO's "inertia" to validate technical documentation before passing it to the Finnish nuclear safety authority, has already estimated its loss on the project at 2.3 billion euros.

Both sides have taken a dispute over payment to the International Chamber of Commerce