The government has abandoned targets to cut congestion

Transport Secretary Alistair Darling wants to set pay-as-you-drive charges using satellite tracking devices fixed to cars.

The tolls would be highest for rush-hour traffic - including commuters, motorway users and school run parents - and on busier routes.

In return, in comments made in the Observer and BBC Radio 4, Mr Darling promised to reduce the overall tax burden for motorists.

It is about getting more out of our existing road space Alistair Darling Transport Secretary

Last year, the government abandoned its target to cut congestion, and predicted traffic jams could increase by up to a fifth by the end of the decade.

In 2006, road charging will be introduced for lorries by using satellite tracking.

Asked on BBC Radio 4's Today programme if that scheme could be extended to private cars, Mr Darling said people would have to be "open minded" about new technologies.

"You either build more roads which will be hugely expensive and environmentally damaging or ask yourself if you couldn't have a different system of pricing," he said.

"It is about getting more out of our existing road space."

But he conceded the technology meant implementation was probably 10 years away.

London's congestion charge has cut journey times

He will be able to examine a nationwide picture of congestion from a study expected to finish next year.

It will pinpoint the areas and times of the country's biggest jams and could form the basis of any charging scheme.

An RAC survey found that 76% of drivers would accept congestion charges if they were "revenue neutral" - that is, if there were associated cuts in petrol and road tax.

Mr Darling said the government would not want to make money out of the scheme.

However the Association of British Drivers was sceptical.

Spokesman Tony Vickers said petrol use would reduce in the next 10 to 20 years as cars moved to pollution-free hydrogen fuel.

"Therefore the government is looking for ways to continue the disproportionate amount of tax they're draining from motorists by finding new ways of taxing them," he told Today.

The civil liberties issue of monitoring car journeys will also have to be addressed.

London scheme

On Tuesday Mr Darling will meet academics and motoring organisations to discuss the issue.

He said among other solutions they would be examining were the introduction of American-style yellow school buses and staggered school opening times.

Currently, one in five cars on the road at 0850 is on a school run.

Mr Darling expressed surprise that more local authorities had not introduced a congestion charge similar to London's, but specifically for rush hour.

Figures released on Friday showed the capital's scheme has cut traffic jams by 40%.