New diesel and petrol cars and vans will be banned in the UK from 2040 in a bid to tackle air pollution, the government is set to announce.
Ministers will also unveil a £255m fund to help councils tackle emissions from diesel vehicles, as part of a £3bn package of spending on air quality.
The government will publish its court-mandated clean air strategy later, days before a High Court deadline.
Campaigners said the measures were promising, but more detail was needed.
The government was ordered by the courts to produce new plans to tackle illegal levels of harmful pollutant nitrogen dioxide.
It came after judges agreed with environmental campaigners that previous plans were insufficient to meet EU pollution limits.
Retrofitting buses
Ministers had to set out their draft clean air strategy plans in May, with the final measures due by 31 July.
Local measures could include retrofitting buses and other transport to make them cleaner, changing road layouts, altering features such as speed humps, and re-programming traffic lights to make vehicle-flow smoother.
Campaigners wanted government-funded and mandated clean air zones, with charges for the most-polluting vehicles to enter areas with high pollution, included in the plans, as well as a diesel scrappage scheme.
It is thought ministers will consult on a scrappage scheme later this year, but there is no firm commitment.
Ministers have been wary of being seen to "punish" drivers of diesel cars, who, they argue, bought the vehicles after being encouraged to by the last Labour government because they produced lower carbon emissions.
The UK announcement comes amid signs of an accelerating shift towards electric cars instead of petrol and diesel ones, both at home and abroad:

Analysis

By Roger Harrabin, BBC environment correspondent
The government plan will not contain a vehicle scrappage scheme. And it won't mandate councils to charge dirty vehicles to enter cities.
Compulsory clean-air charging zones were identified by the government's own experts as the best way to tackle pollution.
And the decision not to include them in the policy leaves the government in breach of a court order to produce a comprehensive clean air strategy by the end of this month.
Ministers argue that it is better to have a scheme for tackling the worst pollution hotspots rather than rushing out a botched comprehensive strategy.
But clean air campaigners will accuse the government of failing to obey the court yet again, having already lost a case on this issue in April.
ClientEarth, the legal group which brought that case, previously warned it would consider going back to court if the government failed to meet its legal obligations to ensure clean air for people to breathe.
Air pollution is thought to be linked to about 40,000 premature deaths a year in the UK, and transport also contributes to greenhouse gas emissions.
A government spokesman said poor air quality was "the biggest environmental risk" to public health in the UK.
"This government is determined to take strong action in the shortest time possible," he said.
Emissions hotspots
"Our plan to deal with dirty diesels will help councils clean up emissions hotspots - often a single road - through common sense measures which do not unfairly penalise ordinary working people."
Environmental law firm ClientEarth welcomed the measures, but said it wanted to see more detail.
Its chief executive James Thornton said: "A clear policy to move people towards cleaner vehicles by banning the sale of petrol and diesel cars and vans after 2040 is welcome, as is more funding for local authorities.
"However, the law says ministers must bring down illegal levels of air pollution as soon as possible, so any measures announced in this plan must be focused on doing that."