Fortum, which agreed to buy the 47 percent stake in Uniper held by former parent E.ON, still needs approval from Russian and European authorities for the planned 3.8 billion euro (3.33 billion pounds) transaction, which Uniper management has opposed.

Schaefer, who faces fresh opposition from Elliott after the activist fund built a stake of more than 8 percent, still said that Uniper would work to create a constructive working relationship between the two companies.

"But I'd like to state clearly that this wouldn't in any way alter our intention to remain an independent company. For the simple reason that it's the best foreseeable course for your company," Schaefer said.

(Reporting by Christoph Steitz; Editing by Maria Sheahan)

Stocks treated in this article : Fortum Oyj, E.ON, Uniper SE