Washington | US annual inflation rate slipped to 3.1 per cent in November from 3.2 per cent, but a key measure watched by the Federal Reserve remained stuck, prompting concerns that the central bank will have to keep interest rates high for longer than financial markets expect.

Core inflation, which excludes food and energy costs and is watched closely by the Fed, rose 0.3 per cent in November, slightly faster than the increase the previous month, leaving its annual rate unchanged at 4 per cent, still twice the Fed’s target rate of 2 per cent.