The transport secretary, Alistair Darling, is seeking cross-party support to legislate for the world's most ambitious road-charging scheme to avert the prospect of "complete gridlock" on Britain's highways.
Under the government's proposals, drivers will have to pay between 2p and £1.30 a mile for each car journey. They will be monitored by satellite, with variable rates levied according to the time, type of road and location.
To mitigate the blow, there would be reductions in fuel tax and vehicle excise duty, although Mr Darling has refused to say whether the overall tax burden on motorists would rise or remain the same.
Mr Darling's proposals, which will be outlined in a speech to the Social Market Foundation on Thursday, were greeted warily yesterday by the Conservatives and the Liberal Democrats. Both parties said they supported road charging in principle but insisted it must not be used as a "stealth tax".
The shadow transport secretary, Alan Duncan, said: "At tempts to cut worsening road congestion are always welcome.
"However, we are astonished that there was no discussion on it in the run-up to the election. I don't imagine the Speaker will be pleased that it is being announced outside parliament."
The Liberal Democrat transport spokesman, Tom Brake, said: "The 'spy in the sky' proposal could be the solution to crippling congestion, but it will be rejected if it is simply another Labour stealth tax. It cannot be a substitute for the integrated public transport system Britain needs."
The government wants to put a bill before the House of Commons within two years for a pilot charging scheme using satellite technology, which could begin in the Midlands or in Manchester by 2010.
Nationwide charging could follow within "ten to 15 years", although Mr Darling cautioned that this would be impossible to impose without widespread public support.
In interviews with several Sunday newspapers, Mr Darling warned that the chronic congestion and pollution of Los Angeles could become common in Britain. "If we don't do anything, it's pretty clear to me we would face complete gridlock. More and more cars will grind to a halt and the generations to come will curse those people of my generation who didn't do anything about it," he said.
No other country has attempted nationwide charging and the satellite technology needed to track cars accurately is still in its infancy. However, Germany has introduced a scheme levying a variable toll on lorry drivers and Britain is working on a similar "spy in the cab" scheme for heavy goods vehicles to begin in 2008.
A feasibility study by the Department for Transport concluded last year that charging all motorists could cut traffic by 4% - enough to reduce the amount of time drivers spend in jams by as much as 46%.
Motoring organisations say charges for rush-hour drivers could be useful in encouraging people to stagger their journeys. But the RAC Foundation pointed out that car owners already pay £42bn annually in tax, of which only £6bn is spent on improving roads.
Bert Morris, director of the AA Motoring Trust, said: "We all believe we can't go on the way we are, because the system is grinding to a halt. But charging on top of the existing fuel tax and car tax is simply not going to be accepted."
Other experts believe charging would be pointless unless it raised extra funds to pay for improved public transport.
Tony Grayling, assistant director of the Institute for Public Policy Research, said: "The government must press for a partly revenue-raising scheme. Otherwise, the growth in traffic on off-peak and rural roads would outweigh the reduction in cities."
Ministers believe that the success of London's congestion-charging scheme and widespread acceptance of the M6 toll road in the Midlands show that the public can be won over to the principle of paying for journeys.
But Stephen Joseph of the environmental pressure group Transport 2000 said Mr Darling was still proceeding too slowly. "I think he could move further and faster on this. In the short term, it still seems to be business as usual - widening motorways without putting in any measures to limit demand," he said.
Why do we need road charging?
The number of cars on the roads has surged by a quarter over a decade to 25m, fuelled by prosperity, frustration with public transport and cheaper cars. Government forecasts suggest that the time drivers spend in traffic jams could rise by 20% by 2010.
Ministers have tried prising motorists out of their cars by increasing tax on petrol but this prompted fuel blockades which brought Britain to a near standstill five years ago.
How will charging work? Cars will contain "black boxes" linked to a satellite which will monitor their every move. Motorists will receive regular bills, charged at variable rates: a Sunday drive down a country road may only cost 2p a mile, but a rush-hour commute around the M25 could be charged at £1.30 a mile. It is hoped this would encourage people to change their habits and avoid commuting by car.
Who will pay for the technology? Many cars already have satellite tracking devices to help drivers find their way. The government believes these will be almost universal before any charging scheme begins in a decade's time. But "retro-fitting" older cars is likely to cost at least £100 each and it is unclear who would foot the bill.
Who will set the prices? This is a moot point. The government is likely to set the fees but motoring organisations want an independent regulator - known, perhaps, as "Ofjam" - to ensure drivers are not exploited.
How much money will it raise? An estimated £9bn annually. Alistair Darling has promised that any charging scheme would be introduced alongside cuts in fuel duty and road tax. But it is unclear how big these cuts would be.
What would the proceeds be used for? Motoring organisations want the money to be earmarked for improvements to the road network. Environmentalists would prefer a system pioneered by London's mayor, Ken Livingstone, in which receipts from the congestion charge have been used to improve public transport.
How popular is the idea? It would face strong opposi tion but most people feel that congestion must be tackled: only 11% believe the present system of road tax works.
Six out of 10 would accept road charging if overall levels of motoring tax do not increase. This rises to 66% if there were "good alternative ways to travel".
Will it really ever happen? Probably, although it may take many years. The Conservatives and the Lib Dems both favour charging in principle, so a cross-party consensus appears possible. But all sides are wary of enforcing road charging without sufficient public support.
A referendum in Edinburgh recently overwhelmingly rejected a city-wide congestion charge, providing a reminder of the strength of feelings on the issue.
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