In a statement, Santos said it has sold a 15% share to Total for $650 million, while Malaysia's Petronas has entered into an agreement to sell a 5% interest to Total.

On completion of the sale transactions, Santos will have a 45% stake in GLNG, Petronas 35% and Total 20%.

Santos has also signed binding LNG offtake contracts with Total and Petronas for 5 million tonnes per annum, representing $100 billion and underpinning the development of a two-train project.

Total will receive 1.5MMtpa of LNG for a period of 20 years, starting in 2014, while Petronas has increased its contracted volumes to 3.5MMtpa under a previous agreement.

Santos chief executive officer David Knox said the sale agreement with Total was a landmark agreement for the Australian LNG industry.

"We are pleased to welcome Total into the GLNG project as a fully integrated joint venture partner," he said.

"Total brings substantial technical LNG plant and project management expertise with respect to major LNG developments.

Knox said the company was also delighted that Petronas had increased its offtake from 2MMtpa to 3.5MMtpa with offtake from both Trains 1 and 2.

"With 5 million tonnes per annum of LNG offtake now secured by binding agreements, GLNG has affirmed its leadership in CSG to LNG development," he said.

Knox added that the project was still targeting a final investment decision this year, subject to all regulatory and partner approvals being in place, and that the company remained in detailed ongoing discussions with Asian parties in relation to further potential LNG sales and equity in the project. The Asian parties include KOGAS.

Santos will use the proceeds of the sale to fund its pipeline of growth projects and general corporate purposes, including its 45% share of GLNG project costs.

Total president Christophe de Margerie said Total would bring its experience in successfully managing major projects such as the construction of liquefaction plants and its capacity to market LNG to the Asian market to the project.

Total and Santos will also explore further potential cooperation between the two companies to commercialise Santos's significant contingent resources in Australia.

The sales agreement is binding and subject to Australian Foreign Investment Review Board approval, other customary consents and regulatory approvals.