Insiders say the big four accounting firms are involved in “perpetrating the greatest tax crimes in history”.

About $US1 trillion in tax revenue is lost worldwide through corporate tax minimisation each year, close to $50 billion of which happens in Australia.

“It's very clear to me that the big four accounting firms are the masterminds of international tax avoidance,” says George Rozvany, who has worked for decades in the corporate tax industry.

“They work with government to deliver what they want for their clients. It's not set in a social context; it's designed to deliver an outcome for their clients.”

Mr Rozvany has worked for Ernst and Young, Coopers and Lybrand (now PwC), the defunct Arthur Anderson, and he was head of tax for chemical giant ICI and insurer Allianz.

Mr Rozvany literally wrote the book (several of them in fact) on transfer pricing – the technique that lets multinationals shift profits from high tax to low tax jurisdictions.

He says sham transfer pricing scheme have spun out of control.

“Transfer pricing behaviour clearly is the greatest concern because it's very easy for a transfer pricing expert to dress up a sham transaction as a real commercial transaction,” he told the ABC this week.

“I'm talking about service arrangements, intellectual property transfers, such as patents or use of patents, and perceived transfer of goods, sham loans between related parties, but in reality it's all about providing services at too high a price which then shifts [income] to a lower tax jurisdiction.”

Mr Rozvany wants the big four to be broken up into eight separate accounting firms and eight tax law practices – a move supported by some European politicians and regulators.

He says existing anti-trust laws may be enough to enforce an “ethical tax principal” to get discounts if they adhere to tax rules and not engage in aggressive tax minimisation practices.

Chartered Accountants Australia and New Zealand spokesperson Michael Croker said the big four accounting firms were not as involved as Mr Rozvany says.

“I don't think there is an ethical free zone that these companies or their advisors can inhabit. They are closely monitored by the ATO, by other regulators,” he said.

“They're backed up by a range of legislative measures which the Government has recently improved in terms of mandatory disclosures, ‘come in for a chat’ type legislation where these companies and their advisors have to go into the ATO and discuss their commercial arrangements and inter-company tax structures that may be suspicious in the eyes of the ATO and the community.

“So they (the big four) are very risk averse, they are very conscious of making sure they stay within the legal parameters and give advice according to the law and, increasingly, within the spirit of the law.”

Mr Rozvany said sometimes there is a disparity between ethics and the law.

“It's an interesting thing, ‘within the law’,” Mr Rozvany said.

“Many things were once legal. Rape and paedophilia were once legal.

“If you set up a sham transaction in a tax haven with a view to shifting profits from a high tax jurisdiction to a low tax jurisdiction that should be considered unacceptable to the international community.”