Speaking to policymakers and clients at an event in Berlin, Deutsche Bank CEO Christian Sewing confirmed the internal probe, noting that "we do have a big interest in continuing to get to the bottom [of both cases]. Hence in the case of Danske, we started another internal investigation."
The Financial Times first reported the story.
According to the Financial Times and other media reports, between 2007 and 2015 Deutsche Bank acted as a correspondent bank for Danske's Estonian branch, which is suspected of laundering €200 billion from former Soviet states. During that time, Deutsche Bank reportedly cleared more than €160 billion through the single, small branch.
The Frankfurt-based lender quit its role clearing dollars for the branch in 2015 after its internal controls began to flag a rising amount of suspicious transactions, which the bank reported to authorities.
Deutsche Bank is the subject of a criminal investigation into suspected money laundering linked to one of its former subsidiaries that was revealed by the Panama Papers data-leak in 2016.
"So far, we do not have any evidence for misconduct on our side," said Sewing, referring both to the Panama Papers investigation as well as the Danske issue.
"We have the highest interest in regaining lost trust," Sewing said. "And we are thankful to the many clients who have stood by us in the past weeks as well."
Shares in Deutsche Bank gained more than 5% on Wednesday on the New York Stock Exchange, rising 37 cents to $8.99.