Deutsche Bank staff broke regulatory rules and company policy to enable clients to siphon off millions of euros in government revenues, according to an internal investigation on its role in one of Europe’s biggest tax scandals.

More than 70 current and former employees are under investigation by public prosecutors in Cologne over the scandal, highlighting the German bank’s exposure to the multibillion-euro “cum ex” tax fraud scheme that is the subject of a sprawling inquiry by law enforcement authorities.

Cologne public prosecutors are investigating 1,500 people as part of a broader inquiry into the scheme, which misappropriated government revenues in a long-running fraud involving leading banks including Barclays, Macquarie and UniCredit’s HypoVereinsbank.