UK energy company Centrica has signed a 20-year deal with U.S.-based Cheniere Energy Partners to import liquefied natural gas (LNG) from the United States.

Centrica will purchase approximately 1.75 million metric tons of LNG per year — enough to supply 1.8 million UK homes — from Cheniere's Sabine Pass liquefaction plant in Louisiana.

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Centrica says it will have the option for a 10-year extension, and the target date for first commercial delivery is September 2018.

"In an increasingly global gas market, this landmark agreement represents a significant step forward in our strategy, enabling Centrica to strengthen its position along the gas value chain and helping to ensure the UK’s future energy security," said Sam Laidlaw, CEO of Centrica. "We are therefore very pleased to have signed this agreement and look forward to working with Cheniere.”