Inflation in Japan hit 4% in December, figures released on January 20 show, though central bank officials remain uncertain that the increases will prove durable.

The figure for consumer price index inflation excluding fresh food – the Bank of Japan’s preferred measure – rose to its highest level since December 1981. Major factors contributing to the rise included energy, durable goods and raw material costs. Inflation is now double the BoJ’s 2% target, though officials had promised to overshoot