Free public transport for all is to be pledged by the Scottish Greens in its election manifesto, The Scotsman has learned.
The radical move would be paid for by measures such as doubling vehicle excise duty for more polluting vehicles and scrapping the freeze on fuel duty.
It follows Luxembourg announcing it would scrap fares from next March and the successful introduction of free bus travel in the French town of Dunkirk.
The Greens will announce on Monday plans for free bus travel for under-21s as a first step towards universal free public transport.
Despite being one of the smallest parties, the Greens influence on transport policy should not be underestimated, having pushed through the workplace parking levy in Scotland as part of a budget deal with the SNP.
The Greens declined to put a timescale on introduction of the policy because of “uncertainty around Brexit and the constitution”.
A spokesman added: “Because we have pitched it at a UK level, we haven’t yet gone into what that would mean at a Scotland level. The policy follows successful trials of free services in other European countries and cities.
“It could be funded through reversing Tory policies that have fuelled a growth in traffic.
“Scottish Greens would double first-year vehicle excise duty on more polluting vehicles, reverse the fuel duty freeze and end support for domestic aviation other than lifeline services to remote and island communities - raising more than £9.5 billion a year.
“All fuel retailers would be compelled to provide charging points for electric vehicles by 2025.”
Scottish Greens co-leader Patrick Harvie said: “To tackle the climate and air pollution emergency we need to focus public funds on public transport, making it the most convenient and easiest choice.
“Imagine how liberating it would be, to hop on and off our buses, trains and ferries at will without the need for fares.
“Free public transport isn’t far-fetched.
“It is happening in cities across Europe and will be in place in whole of Luxembourg by the summer.
“What it requires, though, is political bravery.
“The climate emergency requires an emergency response. That means reducing our heaviest polluters and building a low carbon alternative, fast.”