Japan has kept interest rates on hold at 0.1% as the world's second largest economy tries to overcome deflation.
The Bank of Japan said although its economy is improving, inflation remains a key concern and further government intervention was needed to steer the country to recovery.
The bank's board is forecasting growth of 1.3% for the 2010/11 financial year but said prices are likely to continue their downward movement.
The move comes as rating agency Standard & Poor's revised downwards Japan's outlook from stable to negative owing to concerns over the country's level of debt.
To promote 'long-term investment'
Switching 'hard and expensive'
Smaller funds still packing a punch
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