AN amazing 1.5 million motorists risk having their car seized by police because an insurance data blunder lists them as uninsured, says a top consumer watchdog.

Which? says up to one in 20 of the 34 million vehicle records held by the Motor Insurance Database are inaccurate.

Traffic officers with registration recognition cameras routinely consult the database if they suspect a driver may be uninsured and impound tens of thousands of cars each year.

But up to five per cent of the records supplied by insurance companies to the database may be out of date.

Which? began investigating the loophole after mum-to-be Helen Parry, 29, was left stranded by the roadside in the rain when officers refused to believe she was covered to drive her father's car.

Mrs Parry, a student nurse from Conwy who was 20 weeks pregnant, was fined £200 with six points on her licence and her mother was forced to pay a £105 release fee for the car.

The penalties were withdrawn after her case was taken up by her MP David Jones, who found that 94.4 per cent of records are provided to the database within seven days of a policy being taken out or renewed - just short of a target of 95 per cent.

It means vehicles can be mistakenly identified as uninsured and impounded unless a driver happens to be carrying a valid insurance certificate.

"Glitches have led to the innocent motorists having their vehicles seized and even crushed," says the Which? report. "Up to 1.5 million policyholders can appear uninsured.

"This is due to insurers failing to update the system within the required seven days."

Which? and Mr Jones are demanding bigger penalties for companies that fail to promptly upload details of policies to the database, currently set at a maximum of just £5,000.

Mr Jones, Conservative MP for West Clwyd, said: "Insurers who fail to ensure details are on the database within seven says should receive a more robust penalty."

Latest database figures show 112,000 vehicles were seized in 2007, with almost half crushed or sold for non-payment of fines or release fees.