Estonian prosecutors said Wednesday 10 former staffers of Danske Bank's local unit had been detained following preliminary money laundering charges being pressed against Denmark's biggest lender last month.
Investigators in Denmark, the United States, Belgium and Britain have been looking into the activities of Danske's Estonian unit between 2007 and 2015, with the focus on 15,000 non-resident clients, including many Russians.
Danske has acknowledged that much of the approximately 200 billion euros ($230 billion) that went through the branch during that period may need to be treated as suspicious in origin.
Six Estonians who worked at the bank with alleged links to Azerbaijan and Georgia were detained on Tuesday and another four on Wednesday.
"These are people who were mainly client managers, whose job was to report these money-laundering incidents and to prevent them," Estonia's chief prosecutor Lavly Perling told reporters.
All ten worked at a unit dealing with non-resident clients.
One of the suspects is the former head of Danske's private and overseas banking unit during the period, according to Estonian media.
Two are also suspected of bribery, said Perling, adding she hoped the case would be brought to court soon.
"Estonia was mainly a transit country in the money-laundering scheme," said Estonian criminal police chief Aivar Alavere.
He added that the detained suspects only facilitated the money laundering but "clearly weren't the principal beneficiaries".
Prosecutors, who believe the suspects received money for their acts, said they were seeking permission to seize assets worth 1.5 million euros from them.
Last month Danish prosecutors brought "preliminary charges" against Danske Bank for violating money-laundering laws between February 2007 and January 2016.
They have yet to decide whether criminal charges should be brought against individual members of Danske's top management.
US ratings agency Moody's cut its long-term rating for Danske in October, saying the probe "has increased the probability that Danske will receive substantial financial fines".