Regulators are looking at whether Zeltner's position on Deutsche's board would be a conflict of interest because he is also the chief executive officer of KBL European Private Bankers (KBL epb), a business that overlaps with Deutsche's.

Zeltner, appointed to Deutsche's board in August, will represent the interests of Qatar's royal family - a top shareholder in the German lender. KBL is also controlled by the same family.

Deutsche Bank said in a statement that all potential conflicts of interest that could arise from Zeltner's activities and his relationship with one of Deutsche's major shareholders had been reported to the supervisory board and the company.

"They were reviewed by the Nomination Committee and considered to be low," Deutsche said.

Deutsche's regulators, the European Central Bank and financial markets watchdog BaFin, declined to comment, as did KBL.

The regulators' concerns were first reported by the Sueddeutsche Zeitung.

(Reporting by Frank Siebelt, Hans Seidenstuecker and Tom Sims; Editing by David Evans)