The key consumer price index fell at the fastest pace on record for the second straight month in June, the government said Friday, boosting concern about increasing deflationary pressure amid falling energy costs and sluggish demand in the recession-hit economy.

The core nationwide CPI, which excludes volatile fresh food prices, fell 1.7 percent in June from a year earlier to 100.3 against the base of 100 for 2005, the Ministry of Internal Affairs and Communications said in a preliminary report. It was the biggest fall since comparable data became available in 1971.

The headline reading marked the fourth straight month of decline, and the fall matches the average market forecast of a 1.7 percent drop in a Kyodo News survey.