The rehabilitation clinics, also known as post-acute care clinics and part of the group's hospital project development business Vamed, could be worth as much as 800 million euros ($858 million), according to the report.

Fresenius declined to comment.

The healthcare group's CEO Michael Sen, who took over last October, is cutting costs and shedding non-core units.

He has said the group will focus on generic drugs unit Kabi and hospitals operator Helios, while Vamed and a stake in dialysis business Fresenius Medical Care would be treated as financial investments.

Last month Fresenius agreed to sell its fertility services business Eugin to a consortium led by KKR's reproductive medicine group IVI RMA for up to 500 million euros.

($1 = 0.9321 euros)

(Reporting by Ludwig Burger; editing by Matthias Williams)