The Australian Taxation Office is investigating more than 800 high net wealth Australian clients of the controversial Panama law firm Mossack Fonseca, which is the focus of an unprecedented leak of tax haven records released globally.
More than 11.5 million documents have been leaked from Mossack Fonseca's files, revealing the secrets of hundreds of thousands of clients - including several thousand Australians - covering a period over almost 40 years, from 1977 until as recently as last   December.
The release of the documents on Monday follows a 12-month investigation by media groups including The Australian Financial Review, led by the International Consortium of Investigative Journalists (ICIJ) in Washington.
"Currently we have identified over 800 individual [Australian] taxpayers and we have now linked over 120 of them to an associate offshore service provider located in Hong Kong," the ATO said in a statement to the Financial Review. 
The files show how Mossack Fonseca thwarted Australian regulators and police inquiries, continued to act for individuals accused of fraud and embezzlement, and lobbied actively to prevent Australia from signing agreements that would allow the exchange of tax information with Samoa, a key tax avoidance jurisdiction.
While most investors and corporations who use tax havens have legitimate reasons to use these structures, the leaked records also show some companies domiciled in tax havens were being used for suspected money laundering, arms and drug deals, and tax avoidance.
"Some cases may be referred to the Serious Financial Crime Taskforce," ATO deputy commissioner Michael Cranston told the Financial Review, confirming the Australian link with Mossack Fonseca.
The data includes high wealth individuals "and we are already taking action on those cases", Mr Cranston said.
"ATO intelligence on tax evasion comes from a variety of sources, including from concerned citizens, advisers, partner agencies and international bodies.
"For example, the ATO has raised tax liabilities of around $400 million from data supplied by confidential informants.
"We are also working closely with the AFP, ACC and AUSTRAC to further cross-check the data and strengthen our intelligence."
Mr Cranston said some of the Australians under scrutiny had previously been investigated by the Tax Office but the probe included a "large number of taxpayers who haven't previously come forward".
  The German connection  
The ATO investigation is based on a smaller set of files detailing Mossack Fonseca's Luxembourg operations, which were sold to the German government by a former employee, triggering scores of raids by tax investigators who targeted Commerzbank??? clients in Germany in   February last year.
German newspaper S&uuml;ddeutsche Zeitung???, working with the ICIJ, subsequently obtained much more extensive files, with a total 2.6 terabytes of data for Mossack Fonseca's entire global operations, from an anonymous informant. No payment was made.
Mossack Fonseca told its clients over the weekend that it had brought in external consultants to investigate "an unauthorised breach of our mail server" and warned that "the information that has been accessed from our files has fallen into the hands of reporters from certain media outlets who have been taking information out of context and making false assumptions about the nature of our services".
"They have already contacted us in an effort to confirm their allegations and ask further questions," Mossack Fonseca said. "We have responded in a general manner and have not provided details that would further expose confidential information."
The Panamanian firm is one of the top five global groups providing corporate registry services in 21 low-tax jurisdictions around the world for more than 214,000 companies, trusts and foundations, providing an essential services for legitimate companies and investors, including BHP Billiton.
But the files show that the firm also protects its less reputable clients, keeping Swiss advisory firm Strachans on its books despite a decade of Project Wickenby investigations initially focused on Strachans that led to 46 criminal convictions, including a jail term for a Strachans partner, Philip de Figueiredo.
Another Wickenby target, Rockhampton-born lawyer Peter Borgas, based in Switzerland, remained a valued Mossack client even after he was arrested in Sydney in 2013 (the charge was dropped five months later).
Last   December, Mossack decided it would not act on its probity concerns for a firm controlled by Tan Yixin, a Chinese executive jailed for 3&frac12; years for bribes and leaking secrets to Australia's Rio Tinto, because "the client will destroy us with their comments" in the high-growth Chinese market.
When the Australian Federal Police wrote to Mossack Fonseca's British Virgin Islands office in   July 2012 to enforce an Australian court order to sell a Perth apartment on which a BVI company, Anchorville Holdings Ltd, allegedly held a mortgage, Mossack replied that Anchorville had been struck off in 2007 and asked the AFP to stop sending letters.
Perth entrepreneur Roger Bryer had lived for a decade in the spectacular Perth penthouse, which was tied up in lengthy criminal trials over a $US15 million ($19.5 million) embezzlement case involving Commerzbank. Most of the proceeds had been transferred to Australian accounts controlled by Mr Bryer, to invest. Mr Bryer told police he had no knowledge the money was stolen. It was not suggested that he had acted improperly.
In 2012, the DPP applied to sell the penthouse as part of the proceeds of crime, but Anchorville had been set up as mortgagee on it.
Rebuffed by Mossack Fonseca, the AFP obtained a BVI search warrant in   November 2012. A Mossack executive produced old documentation showing Anchorville was owned by yet another nominee company.
Meanwhile, Mossack had contacted the original registered owner of Anchorville and offered to reinstate the company, for $5487. As part of that reinstatement, new documents were registered in 2013 that showed that Bryer had owned Anchorville since 2001.
Mr Bryer told the Financial Review on Sunday that he had made it clear to the AFP that he controlled Anchorville and the matter had been completely resolved in a confidential settlement with the AFP and DPP on   February 6, 2013.
While Anchorville was set up as a mortgagee company, its mortgage on the penthouse was not valid.
"I have very grave doubts as to whether they were acting legitimately," Mr Bryer said of Mossack Fonseca. "None of it was credible for that company."
But it is Mossack Fonseca's deep links with governments that appear most worrying.
  Government links  
In 1996 Mossack won a 20-year exclusive contract to create and administer offshore companies for the tiny South Pacific island nation of Niue. When international pressure closed this down in 2004, the firm moved to Samoa and New Zealand.
Last year Mossack's offices created secret offshore trusts in New Zealand that owned companies in Panama with a Dubai account, for senior government figures in Malta.
Mossack is also persona grata in Apia.
"As you are aware, we have been deliberately stalling the proposals from OECD countries to enter into Tax Information Exchange Agreements (TIEA)," the chief executive of the Samoa International Finance Authority, Erna Vaai, wrote to the Panama firm in   June 2007.
Mossack had been lobbying against the Australian move to sign a TIEA with Samoa since 2004, warning that offshore companies would abandon Samoa if it did any deal with Australia.
Now Samoa was facing "mounting international pressures" for a TIEA with Australia and Vaai wanted Mossack to help write Samoa's formal response.
Vaai echoed Mossack's arguments that a TIEA was "not in Samoa's interests given it will only benefit Australia as the information flow is only likely to be one way".
While Samoa eventually signed the TIEA with Australia in 2009, in practice Australian information requests to Samoa can take more than three years to process.
The Mossack Fonseca files offer a walk through some of the best known names in Australian business, but this can be misleading, because there is nothing wrong with owning an offshore company, unless there is taxable income that is not disclosed.
  Offshore structures  
In many instances the offshore holdings appear entirely mundane, with no suggestion of impropriety, such as former Toll Holdings boss Mark Rowsthorn in 2007 setting up a British Virgin Islands company, Hendricks Development Ltd, to invest in a Hong Kong company renting apartments.
Filmmaker Chris Noonan and his partner Glenys Rowe held bearer shares in Steppe Films International Ltd, which was incorporated in the BVI in   September 1996, a year after Noonan directed the Australian film Babe, which reportedly earned $US470 million in worldwide box office and video sales.
There is nothing to suggest impropriety in this or in the following examples, but they reveal the web of offshore structures used by the wealthy.
In 2008, Sydney developer George Ghossayn???, who at the time was a regular in the appointment diary of Labor powerbroker Eddie Obeid??? before later switching his support to the Liberal Party, was setting up an offshore partnership with fellow developer Fouad Deiri???, in a BVI company, Fitall Development Limited.
In   September 2013, convicted cocaine dealer-turned-Queensland property developer Joseph Frangieh??? took control of a Seychelles company, Silver Tiger Enterprises Limited.
In late 2011, sports promoter Dominic Galati??? was publicly challenging to replace Frank Lowy as chairman of Football Federation Australia, "because I believe that someone has to be a voice out there for the people that are passionate about this game".
Behind the scenes, Galati was involved in setting up half a dozen companies in Samoa, which were transferred to a new Hong Kong company, Global Wealth Group, controlled by Galati, William Aloisi, John McGeary and Roy Bijkerk.
William Aloisi's website describes him as an investment banker. Mr McGeary is a greyhound trainer, while Bijkerk is a convicted cocaine importer who has built a property empire through Guardian Care Properties.
A remarkable 269 shareholdings of companies in the British Virgin Islands, Samoa, the Seychelles and Panama, almost all of them holding bearer shares, are linked to just four addresses on the Gold Coast associated with family members of Ian Taylor, a New Zealand businessman who, with his father Geoffrey Taylor, has set up shell companies that have since been linked to arms deals, Mexican drug lords and Russia's largest tax fraud.
There has been no suggestion of illegality by the Taylors.
Ian Taylor has previously told Fairfax that "only a small handful" of their companies were misused.
"Clients of certain nationalities are discriminated against only due to their citizenship.