FRANKFURT (Reuters) - Siemens Energy's troubled wind division Siemens Gamesa is planning to cut 4,100 jobs, or around 15% of its staff, the unit's CEO Jochen Eickholt said in an internal letter to staff seen by Reuters.

"Our current situation demands adjustments that go beyond organizational changes. We have to adapt to lower business volumes, reduced activity in non-core markets, and a streamlined portfolio," Eickholt said in the letter.

A spokesperson for Siemens Energy said the company would announce the number of jobs affected once consultations with all stakeholders are done.

(Reporting by Christoph Steitz)