Prices of liquefied natural gas are more than 10 times more expensive than a year ago. An unexpectedly cold winter may force Japanese power companies to buy large amounts for spot prices, which could push up the cost of electricity.

Asian spot prices hit a new record on October 6. China's shift from fossil fuels to LNG, which emits less carbon dioxide, is a factor behind the price hikes.

The Japan Oil, Gas and Metals National Corporation says China imported more than 58 million tons of LNG from January to September, exceeding Japan's 56 million tons to become the top importer for the first time.

The higher spot prices will not have an immediate impact on Japanese utility firms, as they secure about 80 percent of their demand through long-term contracts.

But the Ministry of Economy, Trade and Industry is advising them to secure extra inventories as a contingency measure.