Labour claims its new sustainable investment policy could see the country become a world leader in clean technology - but National believes it would just lose money.
The policy has at its core a $100 million wealth fund, paid for by dividends from privatised assets and new royalty payments from the oil and gas industry.
Labour leader David Cunliffe said the policy would drive sustainable innovation and reduce the economy's reliance on fossil fuels.
"We're looking to power up a smart high-value economy and we're looking to transition to a more renewable energy and clean technology profile."
National Party asssociate finance spokesperson Steven Joyce said says experimental clean-tech investments have lost money the world over.
"Well there's been some rather sad examples of big clean-tech investments by government funds right around the world, in Australia, the United States and Spain.
"And sadly what generally happens is the government makes investments where other people won't, and there's generally a really good reason for that."
The Green Party says Labour's NZ Inc has some synergies with its Green Investment Bank proposal.
Co-leader Russel Norman said Mr Joyce's response demonstrated the problem of National's focus on a pollution economy.
He said Mr Joyce's claims of clean-tech not being a wise industry to back showed he was out of touch.
"Steven Joyce obviously just doesn't get out much. David Cameron in the UK and his Green Investment Bank has had a great rate of return on their investments.
Likewise, the Clean Energy Finance Corporation in Australia had an excellent rate of return on their investments, and all around the world the fastest growing sector in electricity generation is renewable energy."
In addition to investing in clean tech, Mr Cunliffe said the NZ Inc fund, which would be paid for in part by taking greater royalties from oil exploration, could also be used to buy back shares of privatised assets.
"This is a fund that will invest to create the maximum benefit for future New Zealand of strategic assets and clean technologies," he said.
"Some of those might happen to be shares in previous SOEs, but many of them will be in young companies that have particular potential to drive value in the New Zealand economy."
Mr Joyce said Labour seemed to be promising extra revenue from oil exploration to different groups - including the regions and now the NZ Inc fund.
"I think their difficulty is, is that their policies are starting to meet each other coming back the other way."
Mr Cunliffe says a KiwiShare system would also be introduced that would make it very difficult for state assets to be sold in the future.