Mendy comes off contract at the end of the season and has been in talks with Gala about a Bosman move.
However, Ajansspor says Terim has since blocked the move and instead approved a deal for Strasbourg midfielder Jean Bellegarde.
Terim's decision is a boost for Leicester, which remain in new contract talks with Mendy.
Foxes boss Brendan Rodgers has made it clear he wishes to hold onto the midfielder.
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