Nick Griffin, the leader of the British National party, is to represent the European parliament at the UN climate change conference in Copenhagen, which opens next week.

Last night politicians and scientists reacted furiously to news that the far-right politician and climate change denier should be attending the summit on behalf of the EU.

Griffin, who was elected to the European parliament in June, confirmed last night that he would attend as the representative of the parliament's environmental committee. World leaders, including Barack Obama and Gordon Brown, are hoping to forge a new global agreement to curtail greenhouse gas emissions.

Without such a deal, scientists warn that world temperatures will increase by more than 2C by the end of the century, triggering ice cap melting, sea-level rises, widespread flooding, the spread of deserts and devastating storms.

In a speech in the parliament last week, Griffin denounced those who warn of the consequences of climate change as "cranks". He said they had reached "an Orwellian consensus" that was "based not on scientific agreement, but on bullying, censorship and fraudulent statistics".

"The anti-western intellectual cranks of the left suffered a collective breakdown when communism collapsed. Climate change is their new theology… But the heretics will have a voice in Copenhagen and the truth will out. Climate change is being used to impose an anti-human utopia as deadly as anything conceived by Stalin or Mao."

Griffin will be one of 15 representatives chosen to speak on behalf of the EU in Copenhagen. The shadow climate change secretary, Greg Clark, condemned the move last night. "It is utterly ridiculous that someone who doesn't even believe in climate change should be seeking to represent Europe in Copenhagen. The BNP does not command the support of the people of Britain, let alone of the rest of Europe," he said.

A spokesman for the Department of Energy and Climate Change said: "Membership of the European parliament's delegation to Copenhagen is a matter for the European parliament. Its delegates do not represent the UK government or its views. Nick Griffin will not be part of the UK delegation."

Tim Yeo, chairman of the Commons environmental audit committee, said the decision to choose Griffin showed the "bizarre way" the parliament operated. He added: "If the future prosperity of the human race, in the face of climate change, depends on the contributions of people like Nick Griffin, there is little hope for any of us."

Professor Alan Thorpe, chief executive of the Natural Environment Research Council, said Griffin's claim that thousands of scientists dispute the existence of man-made global warming was simply not true. "The intergovernmental panel on climate change draws on the views of most of the world's leading climate scientists and they have been quite clear that the evidence shows, with a high degree of certainty, that human activities are now having a substantial effect on the climate. It is simply not the case that there is a substantial number who do not accept a link."

Bob Ward, of Grantham Research Institute on Climate Change and the Environment, said: "Griffin denies the overwhelming scientific evidence on climate change. This appears to be driven by a dogmatic strand of right-wing ideology that opposes any form of environmental regulation, usually hidden behind the dishonest claim that climate change is a left-wing conspiracy."

Chris Huhne, the Liberal Democrats' home affairs spokesman and a former MEP, said the European parliament always divided up positions on such delegations according to the parliament's political balance. "Griffin was bound to get something at some stage. It is just a shame they didn't send him to Iceland instead."

Critics say Griffin addresses environmental issues when he believes he can use them to advance anti-immigration policies. His party claims that it would improve Britain's transport infrastructure and reduce carbon dioxide levels by reducing the number of immigrants in Britain using roads, cars, trains and buses.

Gerry Gable, publisher of the anti-fascist magazine Searchlight, said Griffin once tried to win over environmentalists in the 1980s. "His core beliefs – that the white race is being threatened by an invading minority – are the so-called principles that have run through his nasty career."