The former Prime Minister of Australia has complained of “bullying” in the debate about climate change.

In a speech in London last night John Howard, the ex-leader of the Australian Liberal Party who led the country from 1996 to 2007, criticised the “religion” of climate change and suggested it was morally wrong for “wealthy” Western countries to dictate what energy sources developing countries can use.

Giving the fourth annual lecture for Global Warming Policy Foundation, a group sceptical of manmade climate change, Mr Howard said: “There has been bullying in this debate. I find particularly offensive use of the word ‘denier’. We all know what that means.”

Describing himself as an “agnostic” on the issue, he referred to some advocates of climate change mitigation as “zealots” for whom “the cause has become a substitute religion”.

He suggested there’s been a “shift” in the debate of late: “The global financial crisis has mugged the global warming debate with a heavy dose of reality…”

He also cast doubt on the likelihood of a global agreement on emissions such as a new Kyoto Protocol any time soon: “The key globally is the attitude of the US. What’s happened with shale is very significant. I don’t think they were ever going to enter a world agreement. I think we’re further away – further than a few years ago – from compact between USA and developing nations on global warming.”

Asked if the UK should follow Australia and scrap green taxes to lower bills, Mr Howard said drily, “You’re inviting me to do an Al Gore.”

He said energy prices in Australia weren’t quite as heated an issue as in the UK currently but claimed scrapping the carbon tax had been a key issue which helped fellow Liberal party man and new Australian Prime Minister Tony Abbott gain power earlier this year.