BHPB said the money will allow completion of front-end engineering and design work (FEED), progression into detailed engineering and design, purchase of long-lead items and most major equipment and placing major facility fabrication contracts.

Full project approval is expected later this year on completion of the final capital cost estimate and project schedule, which will be derived from the FEED studies. The gross capital cost is expected to be in excess of $US2 billion with BHPB contributing about half.

BHPB has a 44% in the field, which is estimated to contain gross proven and probable reserves of 557 million barrels of oil equivalent. BP is the operator of the field and holds the remaining 56% interest.

Oil and gas produced at Atlantis will be transported to a platform at Ship Shoal Block 332 by the Caesar and Cleopatra pipelines in which BHPB has a 25% and 22% stake respectively.

"The commitment to the Atlantis development marks another landmark in the Group's focused deepwater exploration strategy, which continues to deliver value to the company and its shareholder," said president and CEO of BHPB Petroleum, Mr Philip Aiken.