Japan's central bank officials say the producer price index fell 4.2% in June from a year earlier, marking the 15th straight month of decline. 
Officials at the Bank of Japan say this comes as the strong yen has cut the prices of imports, including aluminum and compound fertilizers. As a result, nonferrous metals tumbled more than 17%, and chemical products dropped nearly 9%, according to Japan's (NHK WORLD) radio. 
In addition to the yen's appreciation, falling prices of crude oil, which continued until early this year, also dampened producer prices. Petroleum and coal products plunged 21%, while electricity, gas and water fell 14%. 
The officials say crude oil prices and the yen's value are having a big impact on producer prices, amid minimal change in domestic supply and demand for goods.