Soaring car insurance premiums threaten to price thousands of young and low-income drivers out of the market and spark a sharp rise in the number of uninsured vehicles on the roads, say motoring industry experts.

The annual cost of insuring a car has risen by a third in the past nine months as insurance companies struggle to meet what they say is a swingeing escalation in fraudulent claims and the cost of settling personal injury claims.

An average premium now stands at £704 – an 11% rise in the last three months – but young people and those on low incomes are being hit hardest.

A male driver under 21 seeking to insure his first car can expect to pay at least £1,000 and many insurers are phasing out cheaper third party fire and theft policies for younger drivers or placing the heaviest price rises on them – up nearly 16% in the last quarter.

Motoring groups warn that a consequence of such large increases is likely to be a rise in the estimated 1.5m uninsured drivers on Britain’s roads, as car owners take the risk of detection rather than renew policies at a higher price, despite increasing success by police and the industry in cracking down on those who drive without insurance.

Edmund King, the president of the AA, which owns one of the country’s largest insurance brokers, said: “Third party fire and theft policies are rising at a rate even higher than others and this is precisely the type of policy that is bought by younger drivers, who are already paying larger premiums anyway.

“There is a danger that the extra burden on new young drivers will price them out of the market. And yet a proportion of them will still drive while uninsured. Also, if you live outside the cities and need the car to get to work but are on a modest income, then these types of increases can have a negative effect.”