Theresa May says she will not punish drivers of older diesel cars who were encouraged to buy the polluting vehicles under the Labour government.
A crackdown on the vehicles to tackle poor air quality has been announced by the London mayor, Sadiq Khan, with drivers of polluting vehicles facing £24-a-day charges to drive in central London from 2019.
But the prime minister said motorists who were urged to switch from petrol to diesel under Tony Blair’s government would be taken into account in future plans.
It came after the courts ruled that the government must publish updated clean air plans by 24 April to meet EU quality limits, which are not being met in areas across the country.
May, currently touring the Middle East, said: “In relation to the issue of diesel cars, obviously we will be producing a new air quality plan. We’ve been required to do that by the courts.
“Decisions will be taken when we produce that plan – obviously we will take final decisions as to what we do. But I’m very conscious of the fact that past governments have encouraged people to buy diesel cars and we need to take that into account when we’re looking at what we do in the future.”
Patrick McLoughlin, the then transport secretary, said in June last year that it had been a mistake for Gordon Brown to slash taxes on diesel.
Brown, the then chancellor, reduced duty on low-sulphur fuel in 2001, which contributed to an increase in annual diesel car registrations from 3.45m to 8.2m.
A government report published in April 2016 showed that diesel cars being sold in the UK emit an average of six times more nitrogen oxide in real-world driving than the legal limit used in official tests.
All but the newest diesel cars will face a £12.50 charge to drive in the planned ultra-low emissions zone under Khan’s plans.
Diesel cars that are more than four years old in 2019 and petrol cars that are more than 13 years old will face the charge 24 hours a day, year-round, in an attempt to cut air pollution.
With the congestion charge during weekday hours, the total fee for the most polluting cars to drive through the heart of London will be £24. Buses, coaches and HGVs that do not meet the emissions standards will have to pay £100. The zone will apply to all vehicles except black cabs.