"I have not occupied myself with a plan B," Teyssen said in response to questions during the company's 2018 earnings news conference in Essen, adding he believed it could be proved that there was no danger of market dominance.

The European Commission said last week it would look into concerns about the deal's impact on retail and network activities in Europe.

E.ON would deal with any consequences of demands for asset disposals, he said. Observers expect there will be demands for concessions on E.ON's part.

(Reporting by Vera Eckert; Editing by Michelle Martin)