The Australian Federal Police (AFP) have come under fire for a failure to investigate the BHP Billiton corruption scandal in which the mining giant is alleged to have bribed government officials in Cambodia and China, according to a report published yesterday in the Australian newspaper The Age.

Confidential documents obtained by The Age reveal that US anti-corruption investigators were critical of the AFP and Australia’s corporate regulator, the Australian Securities and Investment Commission, for closing the bribery case in 2011 without conducting any individual investigations after it was referred to them by US investigators in May 2010.

The AFP recently re-opened the bribery case after a self-initiated review, The Age reports.

Documents obtained by the Fairfax Media-owned newspaper show that in May 2010 Australian authorities were warned that US investigators had found evidence that BHP Billiton was allegedly “paying bribes to foreign public officials”.

The claims stem from a Global Witness investigation in 2009 questioning BHP payments to the Cambodian government of $3.5 million, for which the London-based NGO could not trace back to government accounts for mining concessions.

The Age previously reported in March that Prime Minister Hun Sen had closely overseen negotiations with BHP before an agreement on a mining concession for exploration of bauxite in Cambodia’s Mondulkiri province was signed in 2006.

BHP shut down it’s exploration activities in Cambodia in 2009 citing the global financial crisis and Cambodia’s “own poor financial management”,diplomatic cables obtained by The Age reveal.