Prosecutors have dropped their investigation of Austrian National Bank Governor Ewald Nowotny as part of a probe into potential bribery at the central bank's banknote printing unit.

Vienna prosecutors spokesman Thomas Vecsey said National Bank director Peter Zoellner was also removed from the case but the investigation continued into central bank Deputy Governor Wolfgang Duchatczek, chairman of the banknote unit's supervisory board and many others.

The central bank has said none of the members of the banknote unit's supervisory board were aware of any wrongdoing.

Nowotny, also a policymaker at the European Central Bank, had insisted he was unaware of any wrongdoing at the printing unit, on whose supervisory board he sits.

Vienna prosecutors last year widened their probe to include supervisory board members of the banknote OeBS unit. Former staff there have alleged OeBS paid bribes to foreign officials to get contracts from countries including Syria and Azerbaijan.

The national bank suspended top OeBS management in October after a routine internal audit. It cited at the time indications of illegal business conduct or failure to convey information to the supervisory board.

OeBS counts the European Central Bank and national central banks around the world as its clients, according to its website.

Convictions in the case could carry a maximum penalty of 10 years in prison.

The central bank has said OeBS board members knew that the wholly owned unit had paid commissions to help win contracts but assumed these were legitimate.

(Reporting by Angelika Gruber; Writing by Michael Shields. Editing by Jeremy Gaunt.)