Deflation is clawing its way back in Japan, and it's not good news for an economy trying to recover from its worst recession since World War II. Japan's key consumer price index tumbled at a record pace in May, the government said Friday. The core nationwide CPI, which excludes volatile fresh food prices, fell 1.1 percent from the previous year in the third straight month of decline. The result marked the biggest fall since the government began releasing comparable data in 1971. Japan appears to be 'heading for another lengthy period of deflation,' said Richard Jerram, chief economist at Macquarie Securities in Tokyo. Lower prices may seem like a good thing, but deflation hampers growth and can cause consumers to postpone purchases, leading to production and wage cuts. The drop in underlying prices is 'set to be persistent' and can lead to various problems for companies and individuals because interest rates will 'be too high for prevailing economic conditions,' Jerram said in a note to clients. Japan underwent a destabilizing bout of deflation during the 1990s, and again earlier this decade, when the world's second-largest economy struggled to escape from a real estate and banking crisis. After the results, Japan's finance minister Kaoru Yosano expressed concerns about a significant slowdown in demand. 'We continue to monitor price movements, and need to carefully implement economic management to avoid...a deflationary spiral,' Yosano said at a news conference, according to Kyodo news agency. With crude oil prices down dramatically from record highs a year earlier, energy and transportation prices fell sharply in May. Analysts point to the 0.5 percent decline in so-called 'core-core CPI,' which excludes food and energy, as a troubling sign of weakness in underlying prices. The core CPI for Tokyo dropped 1.3 percent in June, suggesting that prices nationwide are headed further south. Prices in the nation's capital are considered a leading barometer of price trends across Japan. 'This is consistent with media reports that large supermarkets are marking such goods down as households turn increasingly defensive amid severe employment and income conditions,' said Kyohei Morita, chief economist at Barclays Capital in Tokyo. Japan's central bank predicts that prices will keep falling for at least two years. In its latest economic outlook report in May, it forecast core CPI to drop 1.5 percent this fiscal year ending March 2010 and another 1 percent the following year. Key indicators next week will offer a more complete picture of the health of Japan's economy. The government will report May industrial production data on Monday, and unemployment and household spending figures on Tuesday. The Bank of Japan will then release its closely watched 'tankan' survey of corporate sentiment on Wednesday. 