Politicians from Labour and the Greens will be joining Prime Minister John Key and his ministers in attending the United Nations climate change conference in Copenhagen.

Mr Key was initially reluctant to go but changed his mind last week as momentum built up for world leaders to attend the conference.

He will leave next Tuesday to join Climate Change Minister Nick Smith and Climate Change Negotiations Minister Tim Groser at the meeting.

Thousands of politicians, officials, media and lobby groups are descending upon the Danish capital as countries try to thrash out an agreement on climate change.

They will now also be joined by Green MPs Jeanette Fitzsimons and Kennedy Graham, as well as Labour MP Charles Chauvel.

Mr Chauvel believed that the prospects of a high level agreement at the conference had risen in recent weeks, while the Green MPs said they were going to hold the Government to account and hoped it would improve its "shameful" response to climate change.

- NZPA