On WednesdayEU antitrust chief Neelie Kroes accused GDF Suez and E.ON of "serious" misconduct in allegedly carving up gas markets linked to their jointly-owned MEGAL pipeline.
Kroes is expected to rule on the case in the next few days.
"For the moment she (Kroes) is making comments a priori on a decision she has not made public yet," Mestrallet said.
The Commission's case against E.ON and GDF Suez was launched after raids on E.ON and the then Gaz de France group -- which merged with Suez in 2008 -- concerning their jointly-owned MEGAL pipeline from southern Germany to the French border.