A "warning shot" has been fired at diesel drivers by the Treasury, a motoring firm has claimed.
The Government will "continue to explore the appropriate tax treatment for diesel vehicles" as part of its commitment to improving air quality, according to the main Budget document.
It added that ministers will "engage with stakeholders ahead of making any tax changes at Autumn Budget 2017".
Green campaigners have called for a diesel scrappage scheme to incentivise owners to give up their motors in favour of greener models to help cut pollution.
Responding to the Government's statement, RAC chief engineer David Bizley said: "The Chancellor has fired a warning shot at drivers of diesel vehicles, with the suggestion in the Budget document that a new tax regime covering diesel could be announced before the end of the year.
"This uncertainty is bound to be of concern to private and business motorists alike, who will be wanting urgent clarity on just what the Government plan to do.
"The RAC will take a leading role in representing motorists when the consultation goes live."
Mike Hawes, chief executive of the Society of Motor Manufacturers and Traders, said: "The automotive industry is investing significantly in new technology to address the issue of air quality, so we look forward to working with Government to encourage the uptake of the latest, low emission vehicles, regardless of fuel type.
"Nearly one in two new car buyers chose a diesel last year and getting more Euro 6 diesels on the road will be part of the solution as we also strive to meet our climate change targets."
There are growing demands on the Government to take action on air pollution, much of which comes from traffic fumes, particularly diesel vehicles, and which is responsible for around 40,000 premature deaths a year in the UK.
British Lung Foundation chief executive Dr Penny Woods said: "Diesel is responsible for much of the filthy air we breathe. There is a huge consensus that urgent action needs to be taken to protect the nation's lung health.
"The absence of a clear plan to slash harmful vehicle emissions means concerns over how we deal with this public health crisis continues to grow."
She added: "The Chancellor has missed an opportunity to tackle air pollution immediately."