The US Federal Reserve has kept interest rates between 0.25 per cent and 0.5 per cent, the rate it has held since December. The Fed said while conditions have improved, the central bank is still waiting for inflation to reach two per cent. In its statement the Fed said it would carefully monitor actual and expected progress toward its inflation goal as it weighed when next to raise rates.Most investors expected rates to remain on hold, and were looking for changes to the Fed's assessment of the economy. In its statement accompanying yesterday's decision, the Fed's Open Market Committee pointed to strengthening in the labour market and improved household spending, as positive signs.