In a speech laying out his party's green agenda, the Labour leader called the transition to clean energy "the race of our lifetime" as he sought to reassure industrial communities that his plans would not leave them behind.

Sir Keir said that 50,000 new jobs could be created in Scotland alone, amid a dispute with unions over his pledge to ban new North Sea oil and gas exploration.

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"I know the ghosts industrial change unearths," he told the audience in Leith.

"As a young lawyer, I worked with mining communities to challenge the Tories' pit closure programme, but deep down we all know this has to happen eventually and that the only question is when.

"So in all candour, the reality is this, the moment for decisive action is now."

Sir Keir said 90% of North Sea oil and gas has already been extracted or licensed to be extracted.

He insisted that not moving ahead with the transition to clean energy would represent a missed opportunity for British workers, following concerns about job losses and damage to the local economy.

"We've got to seize the new opportunities, this is the race of our lifetime and the prize is real," Sir Keir said.

Despite his reassurances, Unite general secretary Sharon Graham said "actions speak louder than words".

"Oil and gas workers need concrete, fully costed plans that will provide cast iron guarantees that they will not be thrown under a bus in the transition to net zero.

"I have said before that we can't have a repeat of the devastation wrought on workers and their communities by the closure of the coal mines.

"Keir is now agreeing with that, but actions speak louder than words. There can be no room for any equivocation - promises are not enough."

Labour's ambition is to make the UK a clean energy superpower by 2030.

It argues the move is central, not only to tackling climate change, but also to reducing the cost of living crisis, growing the economy, improving energy security and creating jobs.

The party has vowed to take up to £1,400 off household bills and £53bn off energy bills for businesses by the end of the decade, aided by the creation of Great British Energy - a new, publicly owned company that will generate renewable sources.

Sir Keir has already pledged to set it up within a year if his party wins the next general election, and today revealed its headquarters will be based north of the border, calling it a "down payment for a new Scotland".

British Industry Bonus 'to create jobs in UK'

The Labour leader also announced a new "British Industry Bonus" - a £500m a year fund for energy companies that agree to manufacture in Britain's industrial heartlands and coastal communities.

The move emulates the thinking behind Joe Biden's Inflation Reduction Act - a landmark package of subsidies for any companies planning to make green products or invest in green energy in the US.

While the Conservatives have expressed scepticism over the measure, Sir Keir claimed the act is "setting the pace", adding: "In seven months they've (the US) created more jobs than we have in seven years, but they're not the only ones and in truth, we've never been on this pitch."

Speaking later to Sky's political editor Beth Rigby, he said the bonus is intended to "make sure that the jobs are here in the UK", claiming that "whenever I go to a windfarm or any other infrastructure project and ask where were these were made, the answer is always somewhere else".

Labour 'doesn't understand climate crisis'

Another central pillar of Labour's green plan is to axe the ban on new onshore wind within months of entering government.

The details were set out just weeks after shadow chancellor Rachel Reeves faced criticism for watering down the £28bn a year spending commitment to fund the changes, blaming rising interest rates and the "damage" the Conservatives have done to the economy.

Environment charity Friends of the Earth praised Labour for being "strong on climate rhetoric" but said clarity is needed on the pace of the fossil fuel phase out and green investment.

The Green Party also questioned the scale of Labour's net zero ambition, after it said it will not roll back any licenses granted by the Conservatives before the next election, including the proposed Rosebank oil and gas field.

The Scottish Greens said this shows they "do not understand the climate crisis".

The party's climate spokesperson, MSP Mark Ruskell, said: "Unless Labour is willing to state categorically that it will scrap Rosebank then they will have lost all credibility on our climate."

He said if the Tories lose the next election, "only Labour are capable of stopping this environmental disaster from going ahead - but they have said they won't".