The Labour Party says New Zealand needs to maintain its independence at climate change talks in Cancun.
International Climate Change Negotiations Minister Tim Groser leaves on Wednesday for the United Nations conference at the Mexican resort city.
The annual meetings are part of the process of working towards an agreement to replace the Kyoto Protocol, when it expires in 2012.
Widely labelled as a failure, the climate change meetings in the Danish capital last year did result in the Copenhagen Accord.
However, the last-minute accord is not legally binding and sets no real targets to reduce greenhouse gas emissions.
Mr Groser says he hopes the Copenhangen Accord can be included in the UN process, but some developing nations which he calls "off the planet" may make that difficult.
Labour's climate change spokesperson Charles Chauvel is in Cancun and says that kind of approach is not helpful in a UN setting.
Mr Chauvel says the problem is that Mr Groser can not separate his climate change and trade roles, and appears to want to align New Zealand closely with the United States in the hope that it will help with trade talks.
Mr Groser says the Cancun conference is not trying to attain the totally impossible task that was set for Copenhagen of agreeing to a full ratifable treaty, but will look instead at steps towards such an outcome.