Wellington, Dec 17 NZPA - Prime Minister John Key has been dumped from a climate change debate in Copenhagen, with Australian Prime Minister Kevin Rudd set to take his place.

The debate was due to be aired on the BBC tomorrow morning NZ time and includes Mexican President Felipe Calderon and South African President Jacob Zuma.

Mr Key's delegation was told of the switch overnight.

Trade Minister Tim Groser said it was an unfortunate development, but little could be done about it.

"It's a bit disappointing, but that's the way the world works," he told Radio New Zealand this morning.

Environment Minister Nick Smith said this week it was a huge honour for Mr Key to be included in such a significant debate.

The debate is due to be aired on BBC World News on December 19 and 20.