04/04/2016 11:12 PM AEST | Updated 15/07/2016 12:51 PM AEST

BHP Billiton And Wilson Security Linked To Panama Papers

(AUSTRALIA & NEW ZEALAND OUT) A human shadow is visible under the Australian Taxation Department logo, 18 May 2004. AFR Picture by TAMARA VONINSKI (Photo by Fairfax Media via Getty Images)
Fairfax Media via Getty Images
(AUSTRALIA & NEW ZEALAND OUT) A human shadow is visible under the Australian Taxation Department logo, 18 May 2004. AFR Picture by TAMARA VONINSKI (Photo by Fairfax Media via Getty Images)

BHP Billiton, Wilson Security and a major electricity company in Australia are now targets of the Australian Tax Office, after leaked documents linked all three companies to a law firm in Panama and the British Virgin Islands.

A Four Corners investigation revealed on Monday night that the law firm Mossack Fonseca assists the financial manoeuvres of big businesses and individuals in the grey area of international financial secrecy, which was best described by Former US Senate Investigator, Jack Blum, on the program.

"Financial secrecy is the centre piece of business, and the skills of the Panamanian law firms are to figure out how to set up a trust here, that owns a corporation there, that owns another corporation somewhere else and create a series of layers that make it very difficult, if not impossible for an investigator to figure out who really owns what and where the money is."

Not only is Wilson Security itself -- which earned more than $400 million in government contracts -- embroiled in the controversial Panama Papers; the papers have also linked the security company back to the Kwok brothers, who have covertly been acting as directors of the company.

The Kwok brothers were charged in one of the biggest bribery cases in Hong Kong's history in 2014. Both brothers resigned from Wilson Security's holding company held in the British Virgin Islands at the time.

But leaked documents reveal that the companies who direct Wilson Security have both brothers listed as directors on their own books.

BHP Billiton and Li Ka-shing, who owns CKI Holdings, which owns a huge part of the electricity market in Victoria and South Australia, have also been linked to the Panama law firm.

"The great irony here is that here is a company that effectively provides light for every South Australian household but is not prepared to have the light shone on its tax affairs," Senator Nick Xenophon said on the program.

The ATO has previously taken CKI Holdings to court over unpaid back-taxes and penalties, which were eventually settled for less than one tenth of the amount originally owed, reported Four Corners.

Xenophon is one of many senators urging the government to crackdown on tax evasion, calling for greater transparency and accountability when it comes to tax affairs. But experts and politicians agreed on the program, there will only be success when laws are changed globally to hold big businesses to account.

"The justification that's provided by a lot of these companies is that, well, we're technically operating we believe within the law so that makes it okay -- I think we have to call that for what it is, and that's bulls***," NSW Labor Senator Sam Dastyari said on the program.

"The reality is that they are operating in a very, very grey area of the law. This isn't a victimless act. Every dollar that's minimised is a dollar that's not going to a school.. and yet these companies are getting away with it, and we're letting them get away with it."

The ATO's tax evasion taskforce, Project Wickenby, are currently analysing some of the leaked Panama Papers.