Japan's Securities and Exchange Surveillance Commission raided the home of an MUFG Bank employee who allegedly leaked insider information, as well as the head office of the major Japanese bank and other places in May, sources said Tuesday.

The securities market watchdog suspects that the MUFG Bank employee in his 30s, who works at the bank's head office in Tokyo, violated the financial instruments and exchange law by providing his relatives with undisclosed information about a client company of the bank.

The law bans people related to listed companies who learn about important information on the firms before announcement from transmitting the undisclosed information to others for the purpose of helping them gain profits or avoid losses.