Some diesel car drivers are reportedly to be offered compensation to scrap or modify high-polluting vehicles, in new Conservative plans to reduce emissions.
A "targeted" diesel scrappage scheme is expected to be announced within the Government's draft plans to tackle illegal air pollution, The Daily Telegraph said.
Under the plans, the paper said car owners would be able to receive cash only if the vehicle to be scrapped was old enough and registered in an area where air pollution was already at dangerous levels.
The paper said the new strategy would be unveiled on Friday, ahead of the May 9 deadline imposed by a judge last week as ministers decided not to appeal against the High Court's rejection of a bid to delay it until after the election.
Environmentalists won a legal challenge against the Department for Environment, Food and Rural Affairs, which argued that a delay was necessary in order to obey "purdah" rules restricting government announcements during the General Election period.
Prime Minister Theresa May's official spokesman has said the plans would be published between Thursday's local government elections and May 9.
Mrs May has in the past indicated that she will not punish drivers of old diesel cars if the Government cracks down on the motors to protect the environment.
Drivers were encouraged to switch away from petrol under Tony Blair's government and Mrs May said that would be taken "into account" in future plans.
Sarah Olney, Liberal Democrat MP for Richmond Park, said it would take "more than hastily cobbled together policies to convince people that the Conservatives care about air quality".
She said: "Thousands of deaths are caused each year from air pollution, yet this government has dithered and delayed.
"On top of this the Conservatives are committed to a third runway at Heathrow that would worsen air quality and blight lives.
"The Liberal Democrats remain united in fighting Heathrow expansion, protecting the environment and improving air quality."