Spain's High Court placed Iberdrola Renovables under formal investigation on Friday as part of a probe into an alleged spying case, a document released by the court showed.
Iberdrola Renovables is a previously listed unit of Spanish utility Iberdrola that was folded into the parent company.
Iberdrola's Chief Executive Ignacio Galan was put under investigation in a process related to the case.
A spokesperson at Iberdrola declined to comment.
(Reporting by Inti Landauro, editing by Nathan Allen)
