Rass was to join the board of Commerzbank, one of the nation's biggest banks, as chief risk officer.

It is unusual for a bank to announce a prospective board member, only to have the person later withdraw after talks with regulators.

The ECB wasn't able to immediately comment. Germany's regulator BaFin declined to comment.

Rass was to join the board as chief risk officer.

Commerzbank said that it would begin the search anew.

The Commerzbank spokesperson declined to comment on any reasons for Rass' decision to not pursue the role.

The bank said Rass would continue as the bank's chief credit

risk officer.

"We respect Ruediger Rass' decision and are pleased that he will continue to be available to the bank," said Commerzbank chairman Jens Weidmann.

(Reporting by Tom Sims; Editing by Madeline Chambers and Friederike Heine)