Mitsubishi UFJ Financial Group said it has fired an employee who allegedly stole as much as ?2 billion ($13 million) from the safe deposit boxes of approximately 60 clients.

The theft took place at two branches in Tokyo over 4? years before it was discovered on Oct. 31, MUFG¡¯s main banking arm said in a statement on Friday. Japan¡¯s biggest bank is investigating the incident and consulting with the police, it said.

The front-line employee was responsible for managing the safe deposit boxes and ¡°took advantage of this position¡± to open them without permission, the bank said. The market value of the damages was ?1 billion to ?2 billion. The person has admitted to the wrongdoing and has been dismissed.

¡°This act not only undermines the trust and confidence that customers have placed in us but also shakes the very foundation of our business,¡± MUFG said, adding that there were no similar incidents in other branches.

The bank is ¡°considering and will swiftly implement appropriate compensation¡± for damages incurred by clients as well as measures to prevent a recurrence, it added.

MUFG is the latest major Japanese financial firm to reveal alleged crimes committed by rank-and-file staff. Nomura Holdings said this week that a former employee has been charged on suspicion of robbery, attempted murder and arson after he allegedly drugged and stole cash from an elderly client at their home in Hiroshima.