SHANGHAI, May 31 (Reuters) - China’s central bank said on Monday that it will raise the FX reserve requirement ratio for financial institutions to 7% from 5%, effective on June 15. The move is believed to be aimed at easing the fast appreciation in the Chinese currency, according to traders. (Reporting by Winni Zhou and Bejing Monitoring Desk; Editing by Toby Chopra) Our Standards: The Thomson Reuters Trust Principles.