Going ahead with the carbon tax July this year could leave the Australian economy in ruins, according to outgoing Future Fund chair David Murray.

Murray, who previously headed the Commonwealth Bank of Australia (CBA), is highly critical of the tax's preset level, which he said would weaken Australia's competitive advantage in the global arena.

As approved by the Parliament, the carbon pricing scheme will start charging $23 per tonne on companies deemed contributor to Australia's carbon emission levels, which then will transition into market-induced pricing after three years.

Set to be targeted by the new tax are companies belonging to the top 500, media reports said.

"The consequence of introducing that tax at that level in Australia today is very, very bad for this economy, particularly in terms of its international competitiveness," Murray told ABC Radio in an interview on Friday.

"It raises costs further within Australia, it reduces our competitiveness for export of energy-related commodities, and it therefore renders us less competitive in the future," he added.

Simply put, adopting the carbon tax this year will hit badly on the Australian economy, Murray said, stressing too that "it is the worst piece of economic reform I have ever seen in my life in this country."

Murray added that Australia should realise that climate change and global warming were not directly caused by the wholesale emission of carbon dioxide, just one of by-products of man's rapid industrialisation in the past two centuries.

The former CBA chief, however, did not elaborate on this claims, ABC reported.

Instead, Murray reiterated his disapprove on key economic policies of the Labor-led government, specifically on introducing the minerals resource rent tax (MRRT) and its handling of the banking industry.

"(The mining tax) was very clumsily introduced, it was very clumsily designed and the timing at the top of the terms of trade was not a good timing," Murray said of the controversial MRRT, which was passed this month by the Australian Senate.

Also, by applying pressures on banks when they raise interest rests independent of that of the benchmark rates set by the Reserve Bank of Australia (RBA), the government was essentially overlooking to the critical role of banks to the domestic economy, Murray said.

"By jawboning their interest rates down when the international cost of funds and the domestic cost of funds has been behaving the way it is, is to render the banks less able to perform their very important role," Murray told ABC.

In a reaction, Federal Treasurer Wayne Swan said that Murray's views did not come as a complete surprise.

"Big reforms like this are tough reforms, they're never easy, and you will get vested interests and people like Mr Murray out there opposing them," Swan told ABC.

Swan added that the government will stood by on economic reforms that it deems would lead to future prosperity for Australia regardless of what experts like Murray think.

And supporting the carbon tax is far from the nature of the soon-to-depart Future Fund head as Swan noted that "Mr Murray is a well-known opponent of the science of climate change."