The Labour Party says it will not be able to strike a deal with the Government on changes to the emissions trading scheme unless proper financial and policy analysis is undertaken.
National and Labour have been trying to secure cross-party agreement about amendments to the scheme on reducing greenhouse gas emissions.
Legislation to create the scheme was passed into law before last year's election, but it has been under review since National took power.
Labour climate change spokesperson Charles Chauvel says there are rumours about a scheme that would devastate the forestry industry, and extend big subsidies to agricultural polluters and heavy emitters of industrial pollution.
Labour could not support that, he says.