In Monday’s budget, Mr Hammond is due to champion £30bn of funding for new roads and road repairs, hailing it “the biggest-ever cash injection for England’s largest roads”.

Yet the chancellor is recycling an old Conservative party announcement, The Independent can reveal – and environmental experts including Greenpeace’s chief scientist said he should have done a U-turn on the party's earlier pledge.

It comes after the landmark Intergovernmental Panel on Climate Change report warned the world has 12 years in which to limit warming to 1.5 degrees. And earlier this month the government cut grants for electric cars and scrapped those for hybrids.

Mr Hammond will say in his budget speech that a £28.8bn fund will be dedicated to strategically important roads such as motorways and major local routes, for improvements, upgrades and easing congestion under the plan, which covers 2020-25. Major new roads could be built too.

He will also set aside extra cash to fix potholes, repair damaged roads, and trial new methods of transport such as electric bikes.

But in the 2015 budget, then-chancellor George Osborne announced that for cars registered after April 2017, all vehicle excise duty would go to a new roads fund from 2020.

Car tax raises about £6bn a year, and calculated across the five years of Mr Hammond’s plan for 2020-25, amounts to £30bn – the sum he will be trumpeting in the budget.

Publicising the move in advance, the Treasury said: “This will be the first time ever that ‘road tax’ will only be spent on roads. Roads are a crucial part of transport infrastructure and it’s right that from 2020 motorists see their road tax directly paying for improvements to their roads.”

But both Friends of the Earth and Greenpeace’s chief scientist Doug Parr said Mr Hammond should have reconsidered Mr Osborne’s plan.

“It’s less than three weeks since we had a very severe warning from scientists on the effects of climate change. When we need to start cutting emissions, how compatible is this roads programme he’s talking about?” said Mr Parr.

It’s very disappointing to see this government announce over and over again a ‘new’ roads programme Sian Berry

“He should have considered the state of nature, of public transport, of pollution and of climate change and done a U-turn.”

Friends of the Earth’s campaigns director Liz Hutchins said: “Doesn’t Philip Hammond read the news? Earlier this month UN scientists warned that we only have a dozen years to prevent catastrophic climate change.

“Yet rather than investing in a low-carbon economy, the chancellor is gearing up to create more pollution that wrecks our climate and damages our health.

“We could be a world leader in building a cleaner, safer future, but government climate policy seems to be stuck in reverse.”

Sian Berry, co-leader of the Green party, said: “’It’s very disappointing to see this government announce over and over again a ‘new’ roads programme that will just make traffic problems worse.

“Building new roads just creates new traffic. Real, green investment in our future would boost walking and cycling, green energy and local public transport.”

Simon Alcock, of environmental charity ClientEarth, said: “Emergency measures to protect our children from traffic pollution would cost £153m, which is a drop in the ocean compared with the numbers the government is allocating to roads.

“Ministers seem unwilling to find money to protect children from traffic pollution around schools but are happy to spend billions on roads.”

The Treasury said the roads fund would help “make journeys quicker and easier for millions of commuters across the country, while boosting productivity and road safety. Congestion costs UK households over £30 billion every year and the equivalent of more than 100 million working days could be lost, between now and 2040, unless action is taken.”

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Councils will receive £420m for potholes and repairs and to keep bridges open. A further £150m will help improve local junctions.

The government’s Transforming Cities Fund will be extended by £680m to support local transport projects such as cycling networks, new buses and trams.

The chancellor is also expected to announce an extra £90m to trial “next-generation” methods of transport, potentially including self-driving shuttle services and electric bikes.

RAC spokesman Simon Williams told The Independent: “It’s great news for motorists. We know from research that there has been a big increase in dependency on the car so roads are important for the country.

“We found 59 per cent of drivers said they would be very keen to take public transport if it was better, but it’s not as affordable, comfortable or frequent as it should be, and many people in rural areas have not choice of how to get to work.”

He said motorists were suffering too much damage to their vehicles from potholes, which also posed a safety risk to others when drivers swerved to avoid the holes.

A Treasury spokesman said the government was not boosting roads in isolation but was also improving air quality.