​BHP Billiton confirms that Petrohawk Energy Corporation (Petrohawk) has filed its 2011
Form-10K with the United States Securities and Exchange Commission (SEC) as required to
comply with its obligations under certain of its Financial Agreements (as defined in its filing)
which remain outstanding following the acquisition by BHP Billiton Limited.

Petrohawk’s financial statements are prepared utilising United States accounting standards
whereas BHP Billiton financial statements are prepared using International Financial Reporting
Standards and include the impact of the purchase price paid for Petrohawk. BHP Billiton
purchased Petrohawk on 20 August 2011 and therefore only consolidates its activities in its
financial statements from that date.