Drivers of older cars could be offered cash or travel cards to encourage them to scrap their vehicles if a new report for the government is heeded.

The Commission for Integrated Transport says drivers of C, D, E and F registered vehicles should be given up to £750 in exchange for their ageing motors.

And, as part of a wide-reaching package of anti-pollution measures, it wants the drivers of less-clean cars to be given incentives to fit catalytic converters.

'Low emission zones'

Its report also recommends that local authorites be permitted to declare "low-emission zones" from which vehicles without catalytic converters would be excluded.

The report follows trials of a similar scheme in Glasgow.

Its author, Professor David Begg - a key advisor to Deputy Prime Minister John Prescott - said cash incentives were the easiest way to lure motorists onto public transport.

"We would like to see a much higher value payment in public transport vouchers - such as three years' worth of non-transferable travel vouchers," Mr Begg said.

"This would help encourage people - hitherto dependent on an old, expensive-to-maintain car - to switch to public transport.

'Action now'

"Inner cities face more air quality problems than anywhere else and that is where we are particularly concentrating our efforts.

"We can't afford to wait for the undoubted improvements that will flow from renewing the vehicle fleet to trickle down to the inner cities. They need action now - particularly on lorries, taxis and buses."

The report has been tenatively welcomed by motoring organisations who say they would be keen to support it once the question of funding was answered.

Kevin Delaney of the RAC Institute: "It is a good, practical report. It makes some very positive proposals for reducing emissions from older vehicles."

But, with a recommended 12,000 London taxi drivers facing costs to modify their vehicles, there is some opposition.

'Antiquated vehicles'

Bob Oddy of the Licensed Taxi Drivers' Association said: "Taxi drivers in London are not given a choice. The Government forces us to buy these antiquated, over-priced vehicles which they now tell us are defective.

"Surely it is the responsibility of the government or manufacturers to foot the bill for any remedial action that is needed."

A spokesman for the Department of Environment, Transport and the Regions said: "This is a useful contribution to the pollution debate but it does not constitute Government policy. We will consider the report carefully."