FRANKFURT (Reuters) - Deutsche Telekom's outgoing chief executive Rene Obermann will join the supervisory board of steelmaker ThyssenKrupp next year, replacing Swiss economist Beatrice Weder di Mauro, a source close to the board said on Wednesday.

Weder di Mauro is leaving because she has been appointed to an expert committee at the European Commission, the source said, following an earlier report by the Seddeutsche Zeitung newspaper.

The change is likely to be announced before the end of the year, the person said, so that ThyssenKrupp's shareholders can approve the move at an annual meeting in January.

ThyssenKrupp, which is struggling to return to profit and fix its finances, declined to comment. A spokesman for Deutsche Telekom said he was unaware of any pending move.

Obermann is due to leave Deutsche Telekom at the end of the year. Deutsche Telekom's supervisory board chairman Ulrich Lehner is also chairman at ThyssenKrupp.

Obermann is due to assume the post of chief executive at Dutch cable group Ziggo in January and is also a member of utility E.ON's supervisory board.

(Reporting by Tom Kaeckenhoff; Writing by Maria Sheahan; Editing by Philipp Halstrick, Greg Mahlich)