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A boat passes between turbines at the London Array, the world’s largest consented wind farm, off southeast England

The UK agreed on Thursday to set a legally binding goal committing the country to steep cuts in carbon dioxide emissions designed to help ward off climate change.

But in a sign of the uncertainties triggered by Britain’s vote to leave the EU, the move was dismissed as potentially “unlawful” by the think-tank founded by Nigel Lawson, the former Tory Chancellor and a member of the Leave campaign’s strategy committee.

Lord Lawson’s Global Warming Policy Foundation said it was wrong for the government to set in law a fifth “carbon budget” committing the UK to cut emissions 57 per cent by 2032 from the levels of 1990.

The goal was “based on the now incorrect assumption that the UK will still be in the EU by 2030”, the foundation said.

It also assumed the UK would remain in the EU emissions trading scheme, the world’s largest carbon market, and be “covered by the EU’s Paris agreement terms”, it said.

The EU has collectively agreed to cut emissions 40 per cent by 2030 as part of its commitment to the Paris climate change accord agreed in December.

“It is our view that the government has behaved unreasonably and should have delayed approval of the budget and reassessed the impacts in the light of the far-reaching changes flowing from the referendum result,” the foundation said in a statement.

“The hasty, rubber-stamping of a budget designed for very different circumstances is dangerous in itself and may be unlawful. The incoming prime minister should review this decision as a matter of priority.”

The UK’s 2008 Climate Change Act requires the government to set five-yearly budgets for how much CO2 can be emitted to help reach the Act’s ultimate aim of cutting emissions 80 per cent from 1990 levels by 2050.

Thursday was the statutory deadline for writing the latest budget into law and the turmoil surrounding last week’s Brexit vote had raised speculation that the government might try to delay.

“Today’s announcement is especially welcome given the uncertainty caused by last week’s referendum,” said Hugh McNeal, chief executive, of RenewableUK, the wind farm industry trade group.

However, the energy department is expected to announce next week that it will abolish a £10m fund set up by the previous coalition government to kick-start urban renewable energy projects.

It is unclear if the move is related to the Brexit vote. The fund has backed more than 60 schemes, mostly solar panel installations, in towns and cities across England since it was set up in 2014.

Lord Lawson is one of a number of influential Leave campaigners who have long questioned the cost of measures to tackle climate change. His foundation says the science of global warming is “not yet settled”.

It is still unclear if the new government required after the resignation of David Cameron as prime minister will maintain existing climate policies.

One of the frontrunners for Mr Cameron’s job, Michael Gove, the justice secretary, has said climate change can have a “devastating” impact on societies but was once accused of trying to downgrade global warming in the national schools curriculum.