Tony Blair has triggered a Labour civil war by claiming the government’s policies for tackling climate change are “doomed to fail”.

The prime minister said attempts to reduce society’s reliance on fossil fuels would only have a “minimal” impact on global warming.

Writing in the foreword to a report by the Tony Blair Institute, he said: “Political leaders by and large know that the debate has become irrational. But they’re terrified of saying so, for fear of being accused of being ‘climate deniers’.”

His remarks are a direct attack on the government’s drive to achieve net zero by 2050 – one of Labour’s flagship policies.

Hitting back at the party’s former leader, a No.10 source told HuffPost UK: “The test for everything this government does is whether it will generate investment, jobs, growth and put money in people’s pockets.

“Keir reformed the Labour Party from a doe-eyed activist party, to a serious pragmatic government. Gone are the days when Labour allow sentiment or ideals to drive policy.

“Net sero is a growth opportunity, and as the PM said last week at the energy summit, we are already seeing the benefits.”

A spokesman for the Department of Energy Security and Net Zero said: “As the prime minister said last week, the clean energy mission is in the DNA of this government – because it is the route to energy security, lower bills, and good jobs for our country.”

Government sources also pointed out that the Confederation of British Industry has pointed out that the net zero sector is growing three times faster than the UK economy as a whole.

In his foreword, Blair said: “In developed countries, voters feel they’re being asked to make financial sacrifices and changes in lifestyle when they know that their impact on global emissions is minimal.

He said the expected rise in fossil fuel use and the doubling of airline travel over the next 20 years undermine current climate policies.

“These are the inconvenient facts, which mean that any strategy based on either ‘phasing out’ fossil fuels in the short term or limiting consumption is a strategy doomed to fail,” he wrote.

His comments came just 48 hours before voters across England go to the polls in the local elections.

Reform UK leader Nigel Farage said they showed his party was “winning the argument” on net zero.

Shadow energy secretary Andrew Bowie said: “It seems even Tony Blair has come to the realisation that Keir Starmer and the Labour Party’s mad dash to net zero by 2050 is simply not feasible, or sustainable.

“As Ed Miliband’s net zero zealotry pushes this country’s energy security even further into the arms of China, and their slave labour supply chains, and risks driving up energy bills further and further, only Kemi Badenoch and the Conservatives are telling the truth about energy policy in this country.

“We have been clear that the cost of net zero by 2050 to families will be far too high, and we must urgently change course. Will Labour now finally be prepared to do the same, and put the national interest above their own ideological dogma?”