The Green Party is pulling out of part of its memorandum of understanding with the Government, saying it can no longer work with it on energy efficiency.
The memorandum, signed in April, covered energy efficiency, home insulation and the regulation of natural health products.
The Greens are also working with the Government on the national cycleway.
Energy spokesperson Jeanette Fitzsimons says she was not advised or consulted about plans to scrap the Energy Efficiency and Conservation Strategy and stop work on vehicle fuel efficiency standards.
She says she rang Prime Minister John Key with her concerns, but nothing changed.
Energy Minister Gerry Brownlee says the Government has introduced a number of new initiatives in the last year designed to encourage New Zealanders to be more efficient with their energy use.
He says he is disappointed the Greens have decided they can't stick with the Government on this issue.
Mr Key is rejecting the claim that the Government did not consult the Greens.
He says there is clearly a philosophical difference of opinion over fuel standards.
Mr Key says the arrangement with the Greens is important, and is working well in other areas.