Political allies and friends of the former leader went to ground on Tuesday following the incendiary speech to the sceptic Global Warming Policy Forum, which is the latest in a series of dramatic interventions from Mr Abbott into the energy debate, including a recent warning that he could cross the floor rather than vote for a clean energy target.

The Coalition has effectively signalled it will not adopt a clean energy target and an alternative policy proposal, designed to ensure greater reliability in Australia's electricity networks and force down prices, could go to cabinet and then the Coalition party room as soon as next week.

In his speech, Mr Abbott also suggested the science of climate change was not settled, that 100 years of photography at Manly beach, in his Warringah electorate in Sydney, suggested sea levels had not risen and that, "environmentalism has managed to combine a post-socialist instinct for big government with a post-Christian nostalgia for making sacrifices in a good cause".

"Primitive people once killed goats to appease the volcano gods. We're more sophisticated now but are still sacrificing our industries and our living standards to the climate gods to little more effect," he said.

Ben Peiser, director of the Global Warming Policy Forum, said "there was nothing loopy in the speech whatsoever, it was very rational" and it was well-received by the 200-strong audience, which included ambassadors from central European countries and Japan, and a number of British MPs.

"I am not saying everything he said I agree with - but that's the point," he said.

The aim of the forum was to provide a "full spectrum of views" on climate and energy policy "and nowadays if you do that you are controversial," he said, adding that he was glad the speech had generated a strong reaction because "that was the whole idea, I think".

"Our aim is to offer people the ability to have a proper debate without all the noise and shouting".

Mr Abbott had been invited to speak partly because "it's unusual for a senior politician to speak frankly about these things," Mr Peiser said. "They usually would say these things in private."

The ABC's London bureau chief Lisa Millar said on Twitter that her news team were "not allowed to hear [the] speech or report on it firsthand in London", having been told it was a "non-media event" - despite parts of the speech being given to News Corp publications in advance. Guardian Australia's editor Bridie Jabour said on Twitter the Guardian was blocked from attending. Fairfax Media also sought attendance but Mr Abbott's office said the speech was by invitation only and not open to the media.

Deputy Labor leader Tanya Plibersek said Mr Abbott had "left the realm of the merely destructive and entered the realm of the loopy. This is actually weird stuff - we know climate change is having an effect in Australia as well. To be denying it in this way seems so bloody minded."

Shadow treasurer Chris Bowen said the speech was an "extraordinary intervention" and that the former prime minister was "calling the policy shots" on the government's move to walk away from the clean energy target.

Fairfax Media spoke to several Liberal MPs who count themselves as friends and conservative allies of Mr Abbott on Tuesday but none wished to speak on the record about the former prime minister's intervention.

Those MPs welcomed the prospect of the government walking away from a clean energy target but dismissed suggestions that Mr Abbott had played a consequential role in arriving at this position.

Greens climate change spokesman Adam Bandt MP said the former Liberal leader was a "dangerous fool who could be simply ignored were it not for his ability to dictate Malcolm Turnbull's climate policy", while environmental groups such as the Climate Council said the speech was out of touch with reality.

Former British Labour leader Ed Miliband responded to the speech with a tweet that said: "I know Donald Trump has lowered the bar for idiocy but....."

Mr Abbott has adopted a variety of positions on climate change in the past decade, including advocating a carbon tax and advocating a vote for Kevin Rudd's emissions trading scheme back in 2009 - before he reversed course and took the leadership from Malcolm Turnbull in the process - campaigning against Julia Gillard's emissions trading scheme, signing up to the Paris Climate agreement and then suggesting that the deal was aspirational only.

Mr Abbott's political ally Craig Kelly dismissed suggestions the former leader was angling for a return to the leadership and that Mr Turnbull would lead the party to the next election during an interview on Sky News.

He added, however, that you could "never say never" about such an unlikely political come back.

The Global Warming Policy Forum has published the text of the speech online and plans to upload a video.