Ed Miliband yesterday branded Tony Blair 'incredibly defeatist' over his warning that Labour's controversial Net Zero drive is 'doomed to fail'.

In a high-profile intervention last month, Mr Blair savaged the Government's obsession with Net Zero, saying voters were being asked to make 'financial sacrifices and changes in lifestyle' that they knew would have 'minimal' effect on global emissions.

The former prime minister said Mr Miliband's drive to phase out fossil fuels was 'doomed to fail'. And he urged ministers to rethink the Government's 'irrational' approach.

His comments came in the foreword to a report on climate change published by his think-tank.

Downing Street declined to criticise Mr Blair at the time, saying that parts of the report were in tune with Government thinking.

But Mr Miliband went on the attack on Friday, saying critics of his agenda were being 'far too defeatist about Britain'.

He said he was 'absolutely determined' to deliver on Labour's Net Zero plans – and suggested they should even be accelerated.

Speaking to the Rest is Politics podcast, Mr Miliband described the former PM's intervention as 'disappointing'.

Podcast host Alastair Campbell, who served for years as Mr Blair's chief spin doctor, revealed that on the day of his intervention last month, Mr Miliband sent him a message asking: 'What the f*** is he up to now?'

Mr Miliband replied: 'The report itself – he wrote a foreword to the report – is perfectly unobjectionable... but what is disappointing about Tony's foreword, and I have huge respect for Tony, is I think it is incredibly defeatist which is not what Tony is. It is really defeatist.

'It sort of says we're not going to succeed, we're not going to achieve 1.5 degrees – the whole thing is, it's all going badly.'

Mr Miliband insisted that global action on climate change was now achieving more than when he previously held a similar role in the last Labour government 15 years ago.

'It is just not true to say the world has not made progress,' he said.

Mr Miliband is in charge of Labour's 'mission' to decarbonise the UK's entire electricity supply by 2030 – a goal which many experts believe is impossible to achieve without incurring ruinous costs.

Trade unions have warned the plan will cost thousands of well-paid jobs in the North Sea oil and gas industry.

On Friday, Mr Miliband vowed to press ahead with his agenda, regardless of the criticism – and insisted that the rest of the world would eventually follow.

'Let's not have a diminished view of Britain,' he said. 'We really matter in this. So many countries come to me and say, you have got a really important responsibility here.'

Mr Miliband suggested there was even a case for accelerating Labour's plans.

'The biggest single risk is that we are held in absolute contempt by future generations,' he said. 

'They will say, you knew – as a generation – about the problem, you knew about the scale of the problem, you saw the wildfires and the heatwave deaths... you knew about the problem and had time to do something about it and you totally f***ed it up, you didn't do it.'