Under the strategy, unveiled by Home Secretary Jack Straw on Wednesday, all car owners may have to fit immobilisers in their vehicles.

But both the RAC and the AA said the decision to fit them should be left up to individuals.

The BBC's Christine Stewart: Car immobiliers may become a legal requirement

Mr Straw wants to cut vehicle-related crime - which costs £3bn a year - by 30% over the next five years.

New vehicles are already sold with immobilisers, which can cut out the ignition, starter motor or fuel pump. They mean cars can only be started using a specially coded fob or key.

Mr Straw said: "Fitting immobilisers is an important way of making your own vehicle much less vulnerable."

Home Secretary Jack Straw: We want to know what people think about the proposal

RAC spokesman Edmund King said: "We would advise motorists to fit the type of security device they can afford and which is appropriate for their car.

"If you've got a top of the range car which might be targeted by sophisticated criminals working to order, get a satellite tracking device.

Jack Straw wants to see vehicle-related crime fall by 30% over five years

"If your car's worth £250 and you can barely afford to run it, do what you can. "We would prefer to see it as a voluntary measure rather than saying immobilisers must be fitted."

The AA also opposed any legal changes. Although the organisation was represented on the Action Team which drew up the proposals, its head of road safety, Andrew Howard, said it had strongly objected to this particular recommendation. But the AA was then overruled.

He added that motorists most likely to be caught by the new law were, almost by definition, the poorest drivers. Many of them would be elderly and many would live in rural areas where cars were essential.

Also included in the crackdown unveiled by Mr Straw was police targeting of car crime "hot spots".

More than one million cars were stolen or broken into last year.

The government is also expected to put £50m into other measures to improve security in car parks, where cars are four times more likely to be stolen than at home or work.

Publication of the strategy coincides with Home Office Research showing the extent of the problem in England and Wales.

The research is expected to show that vehicle crime accounted for 24% of all recorded crime in 1997.

Police proposals

Last year, the Association of Chief Police Officers unveiled its own proposals aimed at reducing the number of car thefts in the UK.

The package included proposals ranging from making it compulsory for drivers to carry their MoT certificates and insurance documents.

More cash is to be spent on security at car parks

ACPO also called for tighter controls on number plate supply and design to make it harder for criminals to change the identity of stolen cars and to increase the number of vehicles recovered.

In Scotland, the country's largest police force, Strathclyde, has been using hi-tech methods in an attempted to cut car crime.

Officers have been using Global Positioning Satellite (GPS) tracking devices and laptop computers to check vehicles.

And in Northern Ireland, the Royal Ulster Constabulary has set up a new squad to tackle the problem of joyriding.