core sector communique

Final Regulatory Approval Received for BHP Billiton’s Tender Offer for Petrohawk Energy Corporation

August 18, 2011

BHP Billiton (ASX: BHP, LSE: BLT, NYSE: BHP, NYSE: BBL, JSE: BLT) and Petrohawk Energy Corporation (“Petrohawk”) (NYSE: HK) announced today that on 17 August 2011, BHP Billiton and Petrohawk received notice from the Committee on Foreign Investment in the U.S. (“CFIUS”) that CFIUS has concluded that there are no national security issues of concern in relation to the transactions contemplated by the merger agreement between BHP Billiton and Petrohawk, including BHP Billiton’s tender offer for all of the issued and outstanding shares of common stock of Petrohawk for US$38.75 per share in cash. As previously announced, on 22 July 2011, BHP Billiton and Petrohawk received notice from the U.S. Federal Trade Commission of early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act in relation to the tender offer. Accordingly, all regulatory approvals conditions to the tender offer have been satisfied.

The documents related to the tender offer have been filed with the U.S. Securities and Exchange Commission (the “SEC”). As previously announced, the tender offer has been unanimously recommended by the Petrohawk board of directors and is being made pursuant to the merger agreement between BHP Billiton and Petrohawk. The tender offer is scheduled to expire at midnight, New York City time, at the end of Friday, 19 August 2011, unless the tender offer is extended or earlier terminated in accordance with the rules and regulations of the SEC and the merger agreement.