A former top official of a credit union in Yokohama has been arrested on suspicion of having stolen more than 600 million yen from its safe-deposit boxes, police said Tuesday.

The case marks the latest in a string of revelations about employees allegedly stealing cash and other assets from safes rented to customers at banks in Japan, such as one under the wing of Mitsubishi UFJ Financial Group Inc.

The police allege Lee Sung Hyon, a former deputy chief of the Yokohama branch of Hana Shinyo Kumiai credit union, stole around 619 million yen in cash from customer safe-deposit boxes in the branch from September 2021 to around March 2023.

Apart from the current charge, the police said they also suspect the 49-year-old may have been involved in the theft of an additional 400 million yen from the boxes.

The suspect was able to open the boxes mainly by using keys he copied without the owners' consent, the police said, adding that he admitted to having spent most of the money he stole on gambling.

The Tokyo-based bank discovered Lee's suspected involvement in the wrongdoing through in-house investigation and reported the case to the police and the Financial Services Agency. It fired Lee in February last year.

Similar thefts by bank employees of customer assets from safe-deposit boxes have been revealed at MUFG Bank and Mizuho Bank since last year.

The police said earlier they believe that more than 1 billion yen in cash and gold ingots worth more than 700 million yen have been taken from MUFG Bank safe-deposit boxes. Mizuho said the amount of stolen cash has reached some 66 million yen.