* Motion by Alecta gets 90.54 pct approval at AGM
* Motion had been widely expected to be rebuffed
* Removal of hurdle could lure back one-time bidder Fresenius
* Shares jump 12 percent post-market (Adds details and share activity)
FRANKFURT, June 12 (Reuters) - Rhoen-Klinikum's owners unexpectedly voted to scrap a requirement for shareholders holding 90 percent of its capital to approve major strategic decisions, which could put the German hospital operator back onto Fresenius's shopping list.
A proposal by Swedish pension firm Alecta at Rhoen's annual general meeting on Wednesday to remove the hurdle, which would also apply for a takeover of Rhoen, was supported by 90.54 percent of shareholders, enough for the motion to succeed.
Shares in Rhoen-Klinikum jumped more than 13 percent in post-market trading.
The threshold, initially introduced to prevent an unsolicited takeover, proved insurmountable when diversified healthcare group Fresenius last year tried to buy Rhoen for 3.1 billion euros ($4.13 billion) in an agreed deal.
"We believe that this clause has turned into a stumbling block for the further development of the company," Marcus Luettgen, a representative of Alecta, told the AGM ahead of the vote on Wednesday.
A removal of the clause from Rhoen's bylaws means future strategic moves will require an approval rate of only 75 percent, as is common in Germany. That could pave the way for a renewed bid by Fresenius, which has said it remained in principle interested in Rhoen.
Alecta's motion had widely been expected to be rebuffed because it required the approval of at least 90 percent of shareholders. Two major shareholders - Asklepios and the owner of medical supplies maker B. Braun - have opposed the Fresenius takeover, and they hold more than 10 percent of shares together.
Rhoen said its management would provide further details on the matter on Thursday.