More than 30,000 jobs are under threat from the government's plans to ban new licences for oil and gas production in the UK, unions have warned.
Delegates at the TUC Congress in Brighton narrowly voted in support of a motion calling for no ban to be implemented before a fully funded plan guaranteeing comparable jobs for all North Sea workers is agreed.
Proposing the motion, Unite and the GMB - the country's second and third biggest unions - said while climate change did pose a risk, fossil fuels should not be abandoned until workers knew how their jobs would be protected.
However, other unions opposed the move, arguing there are "no jobs on a dead planet".
A Department for Energy Security and Net Zero spokesperson said: "The government has a non-negotiable commitment to securing a proud future for the North Sea.
"This includes setting up Great British Energy, a publicly owned energy company headquartered in Scotland, which will invest in technologies that will make us a world-leader in industries that use the expertise of North Sea workers such as floating offshore wind and carbon capture and storage."
Cliff Bowen, who sits on Unite's executive council, told the conference the issue would be "the biggest test of Keir Starmer's mettle".
"Environmental action is required but exporting jobs, skills and destroying working class kids’ futures, while moving production abroad, is just burying our heads in the sand," he said.
Mr Bowen warned of "false promises of green jobs which never seem to materialise".
He compared the "cliff edge" facing North Sea workers to the fate of miners in the 1980s, when many of the country's pits were closed and communities saw unemployment rise.
However, the UK's largest union Unison, which represents workers providing public services, was among those to oppose the motion.
Unison's Jo Tapper told the conference the union supported the need for "a fair transition" to renewable energy, including a comprehensive jobs plan for workers in the fossil fuel industry.
"Workers in the energy sector rightly expect to be heard and protected. But climate change doesn’t only impact on energy workers," she said.
"There are no jobs on a dead planet."
She added: "Jobs and communities can and should be protected by the opportunities created by the rapid expansion of renewables."
In Labour's general election manifesto, the party said it would not revoke existing licences for oil and gas and ensure a "phased and responsible transition in the North Sea".
It said North Sea oil and gas production would be "with us for decades to come" and "managed in a way that does not jeopardise jobs".
However, the party pledged not to issue any new licences because "they will not take a penny off bills" and "will only accelerate the worsening climate crisis".
Meanwhile, delegates also voted overwhelmingly in favour of a wealth tax on the richest 1% of the population to help fund public services and the NHS.
Along with other union leaders, Unite general secretary Sharon Graham warmly welcomed Labour's general election victory.
However, she told the conference that to "fix" the "broken" country left by the Conservatives, the government "need to do more than just move round the deckchairs".
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