Standard Bank Group Ltd., Africa's biggest bank by assets, said it lost as much as 300 million rand ($19 million) to organized fraud in Japan.

The bank has "been the victim of a sophisticated, coordinated fraud incident," the Johannesburg-based lender said in a statement on Monday. "This involved the withdrawal of cash using a small number of fictitious cards at various ATMs in Japan. The target of the fraud has been Standard Bank and there has been no financial loss for customers."

The company is working with authorities and may recover some of the money, it said. "Investigations are at a sensitive stage and further information will be provided as appropriate."