By Inti Landauro

PARIS--Electricite de France SA (EDF.FR) has agreed with the beleaguered nuclear company Areva SA (AREVA.FR) to value its nuclear reactor unit--in which the utility is buying a controlling stake--at a little over 2.5 billion euros ($2.7 billion), officials at both companies said.

The boards of both companies still have to ratify the valuation in the coming days but it is unlikely the amount will change, an official at EDF said Thursday, confirming an earlier report from French newspaper Les Echos.

EDF has agreed to pay an additional sum to Areva, depending on the future profits made by the unit, which represents about 40% of Areva's overall revenue, the newspaper said.

Six months ago, EDF said it had agreed to buy at least 51% in Areva NP, as the unit is called, while Areva said it would keep a maximum 25%. Both companies said they would seek other partners.

The creation of a joint venture between EDF and Areva is part of a broader plan by the government--which controls more than 85% of both firms--to rescue Franc'es nuclear energy capabilities which were once a source of national pride. In recent years, Areva has lost ground to competitors from Russia, South Korea and the U.S. while demand for new nuclear reactors has plummeted.

As part of the operation, the French government has said it will inject fresh capital into Areva. The nuclear engineering firm has said it needs as much as EUR7 billion to balance its accounts.

Areva has lost money for the past four years, dogged by a tough market for nuclear reactors since the Fukushima disaster in Japan in 2011. Difficult market conditions have made it more difficult to recover from a number of poor investment decisions over the past decade and big cost overruns on projects in France and Finland.

China National Nuclear Corp. said late last year that it was interested in taking a minority stake in Areva.

Write to Inti Landauro at inti.landauro@wsj.com

(END) Dow Jones Newswires

January 14, 2016 10:32 ET (15:32 GMT)