French utility giant GDF-Suez SA (GSZ.FR) and most of its partners are pulling out of a nuclear reactor project in Romania because of the lack of a clear regulatory framework and uncertainty about the electricity demand growth in the future, a person related to the matter said Thursday.

GDF Suez, Spain's Iberdrola SA (IBE.MC), Germany's RWE AG (RWE.XE) and the Czech republic's Cez AS (BAACEZ) also decided to withdraw after the Romanian government said it would cut its planned stake to about 20% from the original 51%, the source added. Cez said last week it was withdrawing.

Italy's Enel SPA (ENEL.MI) and European steel giant ArcelorMittal (MT) haven't withdrawn from the project with the others, but it makes little sense for them to stay in the project alone, this source said.

-By Inti landauro, Dow Jones Newswires; +33 1 4017 1740; inti.landauro@dowjones.com.