Rivers of gold: Raids take shine off alleged scam that has cost taxpayers an estimated $200m

The gold flowed from cities across the nation, often collected in furtive deals around Brisbane and transported in suitcases and car boots. Hundreds of kilograms were changing hands every week, so much that questions had to be asked.

It would take more than a dozen raids in two states before investigators with the Australian Federal Police, Australian Crime Commission and Tax Office stopped this river of allegedly illicit gold, uncovering what is believed to be one of Australia's largest organised tax frauds.

The ATO has estimated the elaborate scam cost taxpayers more than $65 million, but industry sources have put the final cost at potentially more than $200 million in faked and misappropriated GST payments.

The unfolding scandal has also provided rare insight into the murky world of private gold trading, an industry where deals worth millions of dollars are done on trust and even a hint of public controversy could threaten to disrupt the supply of gold to the Royal Australian Mint.