Bankers began working on the proposed €35.7bn ($43bn) merger between French utilities Suez and Gaz de France at the end of last summer. According to banking sources in Paris, Suez bankers JP Morgan and Gaz de France's advisers Merrill Lynch began discussions at the beginning of September.

This casts doubt over suggestions that the companies hammered out their plan after learning that Italy's largest power company, Enel, had confirmed its interest in Electrabel, Suez's Belgian unit.