The chancellor missed a key opportunity to take leadership on the climate crisis with his budget, leaving the UK with little leverage to persuade other countries to join in with tougher targets on carbon, green campaigners said on Wednesday.

Incentives for electric vehicles, as well as £300m to tackle air pollution, a £640m fund for nature and climate, cash for carbon-capture technology and a tax on plastic, were outweighed by a massive road-building scheme, no change to taxation for the oil and gas industries, and continuation of the 10 years-long freeze on fuel duty.

The fuel duty freeze alone costs about £9bn a year, and according to Carbon Brief that means emissions are 5% higher than they would be if duty were unfrozen.

Also missing was any attempt to fix Britain’s heat-leaking housing, despite a £9.5bn pot for affordable housing. In the Conservative party manifesto last year there was a commitment to spend £9bn on domestic energy efficiency, which would insulate homes, making them warmer and lowering household energy bills, while also reducing greenhouse gas emissions.

The UK is to host the vital UN COP26 climate talks, in Glasgow, this November, and green groups were hoping the chancellor would set out clear signals as to how the UK would meet its target of net zero emissions by 2050. Doing so is seen as essential in getting other nations to sign up to the tough new carbon commitments needed to drive through COP26 decisions.

“This budget fails to put the UK on track to net-zero emissions, which is a major concern ahead of COP26,” said Ed Matthew, COP26 director of the Climate Coalition. “If the UK cannot get its own house in order it is at risk of crashing the climate talks before they have begun.”

Youth climate activists tried to challenge the chancellor on his way to deliver the budget in parliament this morning, urging him to do more to stimulate the economy through tackling the climate emergency. But they were disappointed.

Fatima Ibrahim, co-executive director of Green New Deal UK, which led the protest, said: “Ahead of COP26 we were hoping today would see a credible and comprehensive plan set out for how the British economy could reach net-zero as soon as possible. Instead, it’s been pushed back – an indication of how seriously this government is taking the climate crisis.”

The government’s commitment to scrapping tax breaks on red diesel, a particularly polluting form of the fuel, was set against road-building – which includes among many schemes “improving traffic flows” on the A303, “unclogging Manchester’s arteries”, and investment in the A46 in the Midlands – and a house-building programme without clear accompanying net-zero emission commitments. Some green groups had urged the chancellor to devote at least 5% of public expenditure to the climate.

Rebecca Newsom, head of politics at Greenpeace UK, said: “Far from ‘getting it done’ for climate and nature, the chancellor has completely missed the opportunity to address the climate emergency. Instead, by announcing £27bn for new roads it seems he’s driving in the opposite direction. Ending the red diesel tax break, and the Nature for Climate Fund announcements, are important steps. But they are just a fraction of what is needed to get the UK on track to delivering net zero before COP26.”

The chancellor was to have announced a new national infrastructure strategy, encompassing hundreds of billions of pounds in public and private sector spending on low-carbon energy, transport, communications.

But shortly before the budget that was put off to an undisclosed date later this spring. Whitehall sources said it was because some spending would have to be reviewed in light of the court ruling that ministers should have taken the Paris agreement on climate change into account when deciding on the Heathrow expansion plan.

Lord Stern, one of the UK’s leading climate economists, said the national infrastructure strategy would mark another key opportunity to put the UK back on track. “The strategy must embody the commitment to net zero emissions and should lead to the rapid expansion in zero-carbon electricity that is required over the coming decades. The UK has a chance to lead the world at COP26. It must lead strongly by example now, and act in the best interests of the whole world as a key element in ‘global Britain’.”