Liquefied natural gas prices may fall by the end of the year as Japan, the world's biggest buyer of the fuel, reopens some of its idled nuclear plants, according to Facts Global Energy.

Immediate supplies of LNG, or spot cargoes, may slip to a range of $15 to $16 per million British thermal units starting in the fourth quarter, Fereidun Fesharaki, the chairman of Facts, said in an interview in Kuala Lumpur Tuesday. Spot prices have risen to as high as $19 per million Btu as Japan boosts imports to replace shut nuclear capacity, he said.

"Japan is starting to reopen nuclear reactors this year and more next year," Fesharaki said at the World Gas Conference Tuesday. "This will bring spot LNG prices down a little bit."