Australian Federal Police issued a press release today alleging "companies fraudulently claimed GST credits and failed to report GST correctly. They formed syndicates to conceal the true nature of their activities and to avoid detection."
GST is a Australian sales tax of 10% that applies to precious metals that do not meet the definition of investment. It likely that the fraud involves scrap gold or silver where GST is payable. Note that it is being classified as "organised crime" which allows the police to invoke proceeds of crime laws so the people behind it can't hide behind the bankruptcy of the companies involved.