Najib Abdul Razak is suing Ambank and its former relationship manager Joanna Yu for taking instructions from and revealing his banking information to 1MDB-linked businessperson Low Taek Jho, also known as Jho Low.

The former prime minister, who is now battling criminal charges related to his three accounts with the bank, is claiming damages from the bank and Yu for allegedly committing the act, which violates the Financial Services Act (FSA) and Banking and Financial Institutions Act 1989 (Bafia)...