Menendez will step down once a new CEO has been named, the bank said.

The lender's board unanimously voted for the decision with the "aim of making more agile and efficient progress in defining the bank's governance model," it added in a statement.

Unicaja, which is controlled by Unicaja Banking Foundation with a 30% stake, said later on Thursday the move would guarantee the "stability and full functionality" of its management until the appointment of a new CEO.

Corporate governance has been at the centre of the recent banking turmoil triggered by the collapse of Silicon Valley Bank (SVB) in the United States and UBS Group's state-backed takeover of Credit Suisse in Switzerland.

Supervisors of euro area banks favour separating the roles of chairman and CEO. At many Spanish lenders, the chairman holds executive powers and controls strategy while the CEO handles day-to-day business.

At the end of 2020, Unicaja announced the acquisition of smaller lender Liberbank to create Spain's fifth-largest bank with around 110 billion euros ($121 billion) in assets.

At the time, the banks said Unicaja Chairman Manual Azuaga would retain executive powers at the merged entity and that two years after the deal's closing, in July 2021, the board would review its corporate governing structure and Menendez's role, while the chairperson would give up his executive powers.

($1 = 0.9084 euros)

(Reporting by Jesús Aguado; editing by David Latona and Richard Chang)