Infrastructure Australia has proposed a user-paid roads system under which Australian motorists would be billed for every kilometre they drive on major roads and highways.

This would replace current fuel excise and registration fees. But motorists would also be hit with current toll fees.

The government agency says the current system for funding roads is unsustainable because drivers are transitioning to electric cars, which will not pay fuel excise, but cost of the roads will stay the same or increase.

The next Australian infrastructure plan will be published in 2021.