The Government is being accused of supporting a 'plan B' which will undermine upcoming talks on climate change.
Australia has suggested an alternative to an international agreement, as it becomes clear a binding deal is unlikely to emerge from next month's conference in Copenhagen.
The 'national schedules' approach would require countries to register their commitments to reduce emissions without binding international targets.
Climate Change Issues Minister Nick Smith says the New Zealand Government's first preference is for a new international treaty but, as a second best, it is preferable to secure something than walk away from Copenhagen without a deal.
Green Party co-leader Russel Norman says internationally binding targets are crucial and taking a 'plan B' to the talks will undermine them.
"What we need are targets based on science, not targets based on what's convenient," he says.
Oxfam New Zealand says the climate talks are very fragile at the moment and if New Zealand starts aligning itself with alternative plans it's going to contribute to a stand-off or even a breakdown in talks.
The summit in Copenhagen from 7-18 December will attempt to draw up a new global climate treaty to replace the UN's 1997 Kyoto Protocol which expires in 2012.