TOKYO (Kyodo) -- A former employee of MUFG Bank was arrested Tuesday over the alleged theft of valuables from customers' safe deposit boxes, police investigative sources said.

Yukari Imamura, 46, is suspected of stealing around 20 kilograms of gold bars worth around 260 million yen ($1.6 million) deposited by two male customers at the bank's Nerima branch in Tokyo around September last year, the sources said.

The former employee, who was in charge of managing safe deposit boxes at some MUFG Bank branches, is believed to have inappropriately used a spare key stored at the Nerima branch, the sources said. The gold was sold to various pawnshops and buyers, with the proceeds used for investments.

According to the bank, the woman is suspected of stealing assets worth over 1 billion yen from some 60 customers over a roughly four year and a half period through October 2024.

The bank said the incident came to light on Oct. 31 after it received an inquiry from a client.

The bank fired the woman, who admitted to having stolen client assets, on Nov. 14 and filed criminal charges against her the following month.