The City watchdog today urged people to check their car insurance after it emerged that thousands could have bought invalid cover.

The call comes after a group known as Sussex Insurance Services was found to be selling motor insurance policies without authorisation from the Financial Services Authority.

It is not known how many people may be affected, but it is estimated that around 18,000 people had bought cover through the Hove-based firm, usually as part of deal when buying a second-hand car.

The Financial Services Authority warned that the insurance was not valid and urged people to buy alternative cover immediately.

The Department of Trade and Industry petitioned the High Court on Friday for Sussex Insurance Services to be put into provisional liquidation, following an investigation by the Companies Investigation Branch.

The court appointed the Official Receiver as provisional liquidator pending the hearing of the petition on December 5.

The DTI is advising people who have paid premiums to the firm to contact the Official Receiver.

People renewing their insurance can ring the FSA's Consumer Helpline on 0845 606 1234 to check whether their new insurer is authorised.