New Zealand's failure to take action to cut greenhouse gas emissions could cost the country between 3 billion and 52 billion NZ dollars (2.29 billion and 39. 77 billion U.S. dollars), according to Treasury figures released by an environmental sustainability campaign group Monday.

New Zealand had a target of a 50-reuction on 1990 emission levels by 2050, but the government had no low-carbon development plan for meeting these targets, as required under a 2010 UN agreement, according to the document released by the Sustainability Council.

It said changes to the country's Emissions Trading Scheme (ETS) in 2012 had resulted in Environment Ministry forecasts that gross emissions by 2030 would be just 0.4 percent lower than if the government had taken no action.

A third period of up to 10 years starting in 2021 was the focus of international negotiations scheduled to be concluded in Paris in December 2015.

"As a small trade dependent nation, New Zealand cannot afford to under-perform and on current projections, any meaningful target for the third period is going to require serious spending," it said.

As a country that relied on food exports and tourism for a living, it had to engage in serious programs to reduce emissions within New Zealand in order to "address credibility risks."

The Treasury report had identified the cost of buying carbon credits to cover a target of a 5-percent reduction below 1990 emissions levels for the 2021-2030 period at a price of between 10 and 165 NZ dollars (7.64 and 126 U.S. dollars) a tonne, the opposition Green Party warned Monday.

"New Zealand families can't afford the cost of inaction," Green Party co-leader Russel Norman said in a statement.

New Zealand had the fifth highest emissions per capita in the Organization for Economic Cooperation and Development (OECD) group of developed nations and they were increasing, he said.

"The longer we delay taking real action on climate change, the higher the cost New Zealand families will pay."

The New Zealand government has come in for international condemnation for withdrawing from the Kyoto Protocol at the end of 2012, gutting the ETS and removing support for sustainable energy technologies.