The Bank of Japan said on Monday that the nation's wholesale prices had retreated 4.2 percent in April from a year earlier, marking the 13th successive month of decline.

The central bank said in a preliminary report that the index of corporate goods prices stood at 99.3 against the 2010 base of 100.

It noted that in yen terms, export prices in the recording period dropped 9.5 percent whereas import prices tumbled 19.4 percent.