The chief executive of Denmark’s biggest bank is resigning amid allegations that its Estonian affiliate was at the center of a major money-laundering scandal.

"It is clear that Danske Bank has failed to live up to its responsibility in the case of possible money laundering in Estonia," Chief Executive Thomas Borgen said in a September 19 statement, as he announced his resignation.

Separately, an internal report into allegations that billions of euros in laundered money from Russia and other former Soviet states flowed through the bank’s branch in Tallinn said that "the vast majority" of transactions between 2007 and 2015 were found to be “suspicious."

The Copenhagen-based bank said it was unable to provide "an accurate estimate of the amount of suspicious transactions made by nonresident customers in Estonia," but it estimated the total flows in the Estonian unit at about 200 billion euros ($234 billion), nine times Estonia’s 2017 gross domestic product.

These flows covered about 15,000 accounts, of which Danske Bank said roughly 6,200 have the “highest risk indicators.”

“Almost all of these customers have been reported to the authorities,” it said.

Danske Bank is already the target of criminal investigations in Denmark and Estonia.

U.S. law enforcement agencies were also looking into the case, according to reports.

Earlier this year, U.S. authorities accused the Latvian bank ABLV of covering up money laundering, leading to the bank's collapse, after it was denied U.S. dollar funding.

Based on reporting by AP, AFP, Bloomberg, dpa, Reuters, and The Wall Street Journal