Japan's economy still has a problem with deflation, and the central bank should keep its easy monetary policy for a while longer, a senior official at the International Monetary Fund (IMF) said on Friday. David Robinson, assistant director at the IMF's research department, said that while adopting an inflation target would be one way to reverse the trend, the IMF recognised the difficulty for the Bank of Japan (BOJ) to take such a policy step. The BOJ has long opposed the idea of setting an