Environmentalists inhabit a "fantasy world" where they would "get rid of technology" and live in Tolkien-esque "wonderful grass huts", Conservative David Davies has said.
Green Party MP Caroline Lucas described Mr Davies as a "fruitcake" after he launched an impassioned speech denying climate change and deriding environmentalists.
But Mr Davies said he was "proud to be a fruitcake", describing the snack as a cheap and reliable source of energy.
The Tory MP for Monmouth attacked environmentalists who refuse to support nuclear energy or shale gas exploitation despite the fact that they reduce carbon dioxide emissions. He likened the green lobby to the Luddites who "smashed up spinning wheels".
"I do wonder and I question what their beliefs are, because I look at the environmentalists, I see them saying to me, the most important thing that we have to do is to reduce our carbon dioxide emissions, but whenever everyone puts solutions in front of them that would reduce carbon dioxide emissions but deliver cheap electricity that we all need, they don't want to know," he told the Commons during a debate on the Queen's Speech.
"And then I see the same people who I know have been marching against globalisation and capitalism, the people in the 1980s who were totally opposed to any form of nuclear deterrent, the people I suspect a few hundred years ago who would have been the Luddites smashing up the spinning wheels.
"These people live in some sort of fantasy world believing that if we could just get rid of technology we could go back to living in some kind of Tolkien-esque world like the Hobbits before the evil ones started attacking them, all living in wonderful grass huts and things. These people are totally opposed to the high standards of living that globalisation and capitalism has delivered to us in the West and is delivering across the whole of the world."
Ms Lucas intervened in Mr Davies's speech, saying it was "rubbish". She said: "I thought that the discussion about Europe was where we found the fruitcakes, I'm finding something else here this afternoon."
Mr Davies replied: "What I say to you also, and to the gentleman nodding his face now, who referred to me as a fruitcake, was that it was the fruitcakes who warned against the euro ten years ago, we were all accused of being fruitcakes then, the fruitcakes were right.
"Fruitcake is a cheap and reliable source of energy, I'm for fruitcakes, I'm proud to be a fruitcake, long may fruitcakes continue."