Scandinavia’s biggest banking group, Nordea, has admitted its Copenhagen office was raided by Danish police as part of an ongoing investigation into alleged money laundering at the firm involving former customers of its international branch.

The bank says it is cooperating with the investigation but has not disclosed much else.

The search by the Danish State Prosecutor for Serious Economic and International Crime (SØIK) over questions regarding Nordea’s anti-money laundering compliance took place on June 12, but the bank only publicly acknowledged the raid a week later.

“At Nordea we take our responsibility for the prevention of financial crime very seriously as a natural part of our daily operations,” said Frank Vang-Jensen, country head in Denmark and a member of group executive management, in a statement. “Nordea will not accept being used as a platform for financial crime, so we are committed to continuing upgrading our defence systems to become even better.”

Nordea’s compliance problems go back at least five years. In 2014, the bank changed its strategy to focus on the Nordic region, in part over concerns it was being used by its international branch customers to launder dirty money.

The bank has said it “exited customers” that didn’t meet its criteria following risk and compliance reviews. It has also invested more than €730 million (U.S. $824 million) within risk, compliance, and resilience and now has more than 1,500 employees working solely on fighting money laundering and financial crime.

In the past year alone, employees have undergone 110,000 hours of training to become better at detecting financial crime, says the bank, which announced in April that it expects to be fined in Denmark for its “past weak AML processes and procedures” and has set aside a €95 million (U.S. $107 million) provision for compliance costs and penalties.

Nordea also faces fines in the United States regarding historical compliance failures relating to U.S. financial sanctions during 2008-2014. In October last year, Sweden’s financial crime unit also received a complaint against Nordea over alleged financial crimes.

Separately, the homes of the former chief executive officer of Danske Bank and other top managers were raided last month as part of the Danish prosecutor’s investigation into the U.S. $230 billion Estonian money laundering scandal.