David Murray, the outgoing chairman of the multi-billion national Future Fund, has savaged the Federal Government’s carbon tax, describing it as the “worst piece of economic reform” has ever seen.


Mr Murray, who is ending his tenure as chairman to be replaced by David Gonski, publically savaged the legislation, describing it as “very bad” for the economy and will quash international competitiveness.


"If you want me to tell you my view, it is the worst piece of economic reform I have ever seen in my life in this country," Mr Murray told the ABC.


"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.


"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."


Treasurer Wayne Swan has defended the tax, describing it as international best practice.


"I just reject what Mr Murray has had to say about this fundamental economic reform which goes to the core of our future economic prosperity,” Mr Swan told the ABC.


"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."