AN anti-theft system that disables a car's keyless entry system is being rolled out by Ford on more of its models.

The security measure has been added as standard to the Ford Puma, as well as to Ford's most electrified vehicle, the Ford Kuga - the company's models with fastest growing sales.

The Ford Mustang Mach-E electric vehicle arriving later in March is also included.

All production of the Ford Puma, which went on sale at the start of last year includes the motion-sensor key fobs. Ford Kuga production of the mild hybrid, plug-in and full hybrid SUV added the deterrent in July last year.

In 2019, the motion-sensor key fobs with sleep mode were introduced to Ford's top sellers the Fiesta and Focus.

The current and previous model Ford Fiesta have been Britain's top-selling car every year since 2008.

More than 1,250,000 new Fiestas were delivered to UK car buyers 2009 to 2020 inclusive, which also meant significant thefts due to its popularity.

Figures from security analysts Retainagroup show how thefts of the latest Fiesta, which debuted the smart fobs two years ago, have fallen by two-thirds compared with the number of previous Fiestas stolen.

From 2009 to 2017 some 3,152 Fiestas were reported stolen but that figure dropped to just 231 last year after the system was launched.

A motion sensor inside Ford's fobs detects when it has been stationary for longer than 40 seconds and triggers a sleep mode, which will not respond to attempts to hack its signal via a relay box or through the misuse of other specialist equipment.

Moving the keyless fob by picking it up inside the home and taking it to the car will restore full functionality by the time drivers approach their cars.

Ford says the fobs are designed to operate only within a two-metre radius of the cars they are bonded to.

Simon Hurr, Ford security specialist, said: "The online availability of devices, which have no place in public hands, has long been a problem for Ford, our industry and crime fighters. We are pleased to extend our simple but effective solution, to help protect more owners of our most popular cars."

Existing models can have security upgraded with replacement sleep-mode fobs, priced between £74 and £94 for Fiesta and Focus, plus 0.9 hours labour to programme and test. The keys are available to owners of the latest Fiesta, on sale since 2017, and the Focus introduced in 2018.