Thieves are stealing cars in just 10 seconds, more than six times faster than a decade ago, according to a new study.

Insurance firm LV= said criminals now preferred to steal keys and drive a car away quickly, rather than force the ignition.

The study, which involved interviews with over 200 convicted car thieves and victims, revealed a growing trend of keys being stolen from an owner's home during a burglary.

The research suggested that up to 40% of car thefts go unreported in official figures as they are classified as burglary if keys were stolen from a house.

Some thieves now lift cars onto trucks before driving it away. One told researchers: "Flat bed truck and a luminous vest and people think you're a clamper. They're lifting more for tax and insurance now, so as long as you look the part, no-one cares."

London tops a league table of car thefts, followed by the West Midlands and Greater Manchester, said the report.

John O'Roarke, managing director of LV= car insurance, said: "Improvements in car security mean that criminals now place a greater emphasis on stealing the keys rather than forcing the ignition.

"There are some basic things that motorists can do to try and prevent theft, such as parking in well lit areas, fitting the car with security devices, and keeping car keys out of sight and out of reach."