Danske Bank's money laundering scandal spread on Friday as Britain's National Crime Agency (NCA) said it is investigating the use of UK-registered companies.
"This is a giga scandal," European Union Competition Commissioner Margrethe Vestager said, joining a growing chorus of calls for a clampdown on the billions of euros which are alleged to have been "washed" through European banks.
An NCA spokeswoman said the British agency was working with partners across government to restrict the ability of criminals to use UK-registered companies in money laundering.
British and Russian entities dominate a list of accounts used to make €200bn in payments through Danske Bank's branch in Estonia between 2007 and 2015, many of which the bank said this week are suspicious.
By 2013, the number of UK-registered customers in the branch's non-resident portfolio had topped 1,000, Danske Bank's investigation revealed, ahead of clients from Russia, the British Virgin Islands and Finland.
As the scope of the alleged money laundering through Danske Bank has widened, investor concerns over the potential penalties it could face have increased, with particular focus on what action if any U.S. authorities might take against the bank.
So far the United States has not said whether it is investigating, although Danske Bank Chairman Ole Andersen said that the lender had made an assessment of whether it violated any US laws. He has declined to share the bank's conclusion of this.
"We need to do more to prevent money laundering from happening," Vestager told reporters in Copenhagen following the resignation on Wednesday of Danske Bank CEO Thomas Borgen after an investigation commissioned by the bank exposed past control and compliance failings.
Borgen, 54, was in charge of Danske Bank's international operations including Estonia between 2009 and 2012.
He said on Wednesday that he had been "personally cleared from a legal point of view" while Danske said its board had not breached their legal obligations.
The European Commission last week recommended banking supervision changes, including bolstering national authorities, but stopped short of setting up a new financial crime agency called for by the European Central Bank.
In a sign of the growing pressure on Danske Bank, which already faces criminal inquiries in Denmark and Estonia, the chief executive of CARE Danmark said on Twitter that the Danish charity had decided to end its relationship with lender.
International aid charity Oxfam also called on Danish municipalities to cut ties with the bank, saying it has not been able to re-establish the trust of Danish citizens.
The mayor of Aalborg, Denmark's third largest municipality, said he would discuss its partnership with Danske Bank at the next municipality committee meeting, but noted that there were only two banks in Denmark would be able to handle a municipality its size.
"Danske Bank has been involved in money laundering which is deeply reprehensible and outrageous but Nordea has been involved in tax havens, so the entire bank sector needs to clean up for us to have a trusting collaboration with the banks," Thomas Kastrup-Larsen said.
Danske Bank's tiny Estonian branch accounted for as much as 10 percent of group profit during the period when suspected money laundering was conducted via its operations there.