Japan's core consumer price index (CPI) rose 1.5 per cent in May from a year before, recording the fastest increase in more than 15 years, the government said Friday.

The core CPI, which excludes fresh food prices, came to 101.6 against 100 for the base year of 2005, the Ministry of Internal Affairs and Communications said in a preliminary report.

The reading came against an average market forecast of a 1.4-per-cent rise.