A Heathrow congestion charge is reportedly being considered under plans to make millions of passengers leave their cars at home when the airport’s third runway is built.

Motorists face being “fined” for driving on 81 miles of roads surrounding the airport as part of proposals to combat gridlock on roads and promote greener public transport.

The charge will be implemented within a decade if levels of nitrogen dioxide from car exhausts fail to drop within legal limits just north of the airport.

The levy could be similar to the central London congestion charge, which costs £11.50 a day, The Times reported.

A spokesman said: “It could be implemented as a means to reduce traffic congestion levels and improve air quality for local communities while raising money for public transport improvements.”

It forms part of proposals to tackle pollution in the area after the government’s decision to approve a new north-west runway at the London hub.

The expansion will allow the airport to accommodate 740,000 flights a year — about 50% more than the current limit. Passenger numbers are expected to almost double to 130 million a year by 2050.

The number of public transport routes will increase, with a new direct rail link from Reading and another south of the airport into Waterloo station.

A station for London’s east-west Crossrail line will also be opened, bus routes will be extended, more charging points will be created for electric vehicles and car-sharing clubs for airport staff will be promoted.