The Danish Business Authority launched a formal inquiry into the external auditors that approved Danske Bank A/S' annual reports while billions of dollars were allegedly being laundered through the bank's Estonian subsidiary, Bloomberg News reported Oct. 5.

The authority will look into whether auditors violated money laundering rules between 2007 and 2015 but will focus the investigation on the bank's 2014 report, the news outlet noted.

The company's "internal review indicates that there may have been breaches of money laundering laws and auditor laws in connection with the bank's external auditing," the watchdog said. A spokesman for the authority declined to provide a reason for the focus on the 2014 report.

Danske Bank's auditor for the 2014 report was Ernst and Young LLP, which said it will fully cooperate with the investigation. Bloomberg said the Danish lender changed its auditing firm multiple times during the period in question.

"While we can't comment on individual client work, EY is confident that its audits and reviews of Danske Bank's consolidated financial statements were appropriately planned and performed in accordance with applicable professional standards," an Ernst and Young spokesman said.

Meanwhile, Morten Mosegaard, the bank's interim CFO, said U.S. authorities' involvement in the money laundering inquiry is very different from the situation at Latvia-based ABLV Bank AS, which collapsed after it was denied dollar funding amid accusations of covering up money laundering, Reuters reported.

His comments follow American investor Bill Browder sending a letter to the U.S. Treasury urging it to investigate the scandal-ridden Danish lender and consider taking action under the USA Patriot Act, which was also used in the ABLV case.

Danske Bank said Oct. 4 that the U.S. Justice Department has initiated a criminal investigation into its Estonian branch.