OTTAWA, June 9 (Reuters) - The Bank of Canada on Wednesday left its key interest rate unchanged at 0.25%, as expected, and said it would maintain its current policy of quantitative easing. The central bank reiterated its guidance that rates would remain unchanged until at least the second half of 2022. It made the comments in a regular rate decision statement. (Reporting by Julie Gordon in Ottawa Editing by Chizu Nomiyama) Our Standards: The Thomson Reuters Trust Principles.