Compañía Española de Petróleos, S.A.U. (Cepsa) is planning to acquire 12% stake in Medgaz, S.A. from GDF Suez S.A. (ENXTPA:GSZ), Medgaz told Reuters. GDF Suez is also in talks to sell some stake in Medgaz to Gas Natural SDG SA (CATS:GAS), two sources with knowledge of the matter said.