Aramco and Commonwealth LNG have signed a long-term contract for the US LNG developer to supply the world's largest oil exporter with 1 million metric tonnes per annum (mtpa), three people familiar with the deal told Reuters.

The deal includes an option for Aramco to double the volume to 2 mtpa.

Aramco wants to become a major liquefied natural gas player, especially in the US, where LNG capacity is set to almost double over the next four years.

It has already signed deals with other US players including NextDecade's Rio Grande LNG project.

Commonwealth LNG is looking to build the country's first integrated LNG export facility in Cameron, Louisiana, with its major shareholder Kimmeridge selling gas from Eagle Ford shale production to the plant.

The deal will bring the LNG developer closer to the 8 mtpa it wants to sell out from the proposed facility's total capacity of 9.5 mtpa ahead of construction.

The firm is targeting the end of the first quarter to make a positive final investment decision on the project.

Aramco is targeting 20 mtpa of LNG capacity to eventually sell into the global market, with 4.5 mtpa currently in progress, Amin Nasser, Aramco President and CEO, said in a call with analysts last August.