A cache of leaked files shows prominent Australians, including business people and celebrities, are among thousands identified as having held secret Swiss accounts with one of the world's largest banks.
The files, released by the International Consortium of Investigative Journalists, show the Swiss arm of HSBC had almost 500 clients linked to Australia, with 856 accounts, and total combined holdings of about $US959.2 million ($1.24 billion).
One client with connections to Australia had accounts worth $US142.9 million ($184.21 million).
The data in the ICIJ report was secreted away by former HSBC employee Herve Falciani, who turned the information over to the French government in 2008 after which its tax authority launched an investigation.
Australians named include the late media baron Kerry Packer, model Elle MacPherson and former ANZ chairman Charles Goode. There are others with adverse findings against them at the hands of regulators or the courts.
According to the ICIJ report, Mr Packer was the beneficial owner of a client account under the name of C.P. International Management Services Limited, set up in 1994, closed in 2000 and linked to his Consolidated Press media empire.
Mr Packer died in 2005.
Ms MacPherson is listed as a model, entertainer and entrepreneur.
The report says Ms MacPherson was connected to seven HSBC client accounts, and was the beneficial owner of five.
"The four client accounts still operative in 2008 were linked to 25 bank accounts that together held as much as $US12.2 million ($A15.73 million) in 2006/2007," the report said.
In a statement, Ms MacPherson's lawyers say she "is an Australian citizen who has accounted for UK tax on the basis of full disclosure in accordance with UK law".
Three of the accounts for which she was the beneficial owner were closed in 2000, 2001 and 2004.
Mr Goode said his account was never used.
"There were no deposits (expect to open it) and no withdrawals (except to close it)," Mr Goode said in a statement to The Guardian.
There is no suggestion that any of the individuals have broken the law.
However, while it's not illegal for Australians to hold Swiss bank accounts, the report raises concerns about the potential for high net worth individuals to used them to avoid or minimise tax.
International tax avoidance was a key issue at the G20 leaders summit in Brisbane in November with world leaders vowing there would be crackdown.
Treasurer Joe Hockey said then the leaders were "very determined" to eliminate tax avoidance, particularly by multinational companies.
"Wherever companies engage in extraordinary activity in order to avoid tax, we will go after them," Mr Hockey said.
'Hundreds of Australian clients'
The files name around 470 clients from Australia, linked to nearly 900 bank accounts, totalling almost $1 billion dollars.
In Australia, a response is being sought from the Tax Office as to whether it had already received data covering Australian account holders and, if so, to what extent it had acted on that information.
Gerard Ryle from the ICIJ said the intelligence was significant.
"Some of these accounts are linked to separate offshore entities,” he said. “It's really an incredible amount of intelligence that the authorities can get hold of, that they wouldn't normally get, say, if they were asking directly from the Swiss government."
"You only get the answers to the questions you ask. And if you don't know that an account, for instance, is linked to a British Virgin Island company, then the Swiss authorities may quite legitimately say, ‘This account does not belong to X, it belongs to this British Virgin Island company’.
“What this data tells you is that behind that British Virgin Island company is actually an Australian citizen. And that's the kind of information that authorities wouldn't have known without this leak."
He said that tax treaties, such as a revised agreement between Australia and Switzerland, which came into effect last October, were "only of limited value".
But Helen Wicker of Crowe Horwath Accountants disagreed, saying that the Australian government could now be more general in its inquiries, and could now ask Swiss authorities to seek additional information beyond what they already had.