BERLIN (Reuters) - The chief executive of Germany's Uniper UN01.DE, Klaus Schaefer, will take a break from running the company while he is being treated for cancer, the utility said.

Klaus Schaefer, CEO of German energy utility company Uniper SE attends a news conference in Duesseldorf, Germany, March 8, 2018. REUTERS/Thilo Schmuelgen

“Klaus Schaefer has informed the Chairman of the Supervisory Board, Dr. Bernhard Reutersberg, that he is suffering from cancer and that the treatment will take several months,” Uniper said in a statement on Wednesday.

Uniper’s supervisory and management boards will now arrange how to divide up Schaefer’s duties during his absence, the company said in a short statement.

Schaefer, 51, has been CEO since Jan 1, 2016, when the company began operating as a separate unit of E.ON EONGn.DE.

He has vowed to defend the energy group's independence, after Finnish rival Fortum FORTUM.HE agreed a 3.8 billion euro deal to buy around 47 percent of Uniper from E.ON.

His opposition to the deal had prompted activist investor Elliott to try to launch a probe into whether managers had actively worked to obstruct the sale. A vote on the motion was delayed in June, leaving the fate of Uniper management in Fortum’s hands.

Fortum said last month that it was seeking to reset its relationship with Uniper.

Carmaker Fiat Chrysler FCHA.MI had to scramble to appoint a successor to its chief executive, Sergio Marchionne, last month when it emerged he was seriously ill and died within days.

After a Swiss hospital said it had been treating Marchionne for more than a year, questions were raised about how much the company knew before it made the situation public.

Fiat Chrysler said that, due to medical privacy, it had no knowledge of the facts relating to Marchionne’s health.