TOKYO, April 1 (Reuters) - Japan's second-biggest utility, Kansai Electric Power Co, said it had signed a 20-year contract to buy 400,000 tonnes per year of U.S. Cameron liquefied natural gas (LNG) from trader Mitsui & Co at U.S. Henry Hub-linked prices.

The Osaka-based firm said it would buy for 20 years from the project's planned launch, scheduled for late 2017.

LNG imports by Japan, the world's top buyer of the super-cooled fuel, have jumped since the Fukushima nuclear disaster, with utilities looking to boost supplies from North America to diversify supply sources and lower prices.

The deal marks Kansai's second purchase of U.S. shale gas. It has agreed to buy 800,000 tonnes per year from the U.S. Cove Point export plant in Maryland.

The U.S. Energy Department in February approved exports from Sempra Energy's Cameron LNG project as the Obama administration moves forward with its goal of expanding the global market for the fuel.

(Reporting by Osamu Tsukimori; Editing by Joseph Radford)