Motorists caught holding a mobile phone while driving face an instant fine from December 1.

But research by the RAC suggests many people are still in the dark about what they will and will not be able to do.

The new law makes it a specific offence to use a hand-held phone or similar device when driving.

It forbids such use even when the car is stopped at traffic lights or in a jam.

Cradling the phone between ear and shoulder to make a call is also prohibited.

But using hands-free equipment is still allowed, provided the phone is operated without the driver holding it.

The new regulation applies to drivers of all motor vehicles including cars, motorcycles, goods vehicles, buses, coaches and taxis.

Cyclists are not included although the police do have powers to deal with careless or dangerous cycling.

Phil Brown, of Swindon-based Safeway Driving School, said he believed the ban would reduce the number of accidents.

Mr Brown said his instructors were busy informing pupils about the new law in time for the December 1 deadline.

"All our instructors know you don't phone and drive at the same time," he said.

"A mobile phone is a necessary evil in today's life, and it can be frustrating that we can't use it in the car, but professional drivers, including instructors, are disciplined enough not to."

A survey by the RAC found one per cent of motorists mistakenly believed using a hand-held mobile would still be legal after December 1.

Three per cent thought cradling the phone between shoulder and ear would be permitted.

And 15 per cent were under the false impression that investing in a simple earpiece and wire attached to the back of the phone would still be legal, even though the driver would still need to handle the phone to use it.

Of those motorists who were aware of the impending law change and did not own hands-free equipment, five per cent said they intended to do nothing about it and continue to use their mobile phone illegally.

These drivers could face a fixed penalty of £30 or a fine on con-viction of up to £1,000 for persistent offenders.

Company bosses might be liable for prosecution if they caused or permitted employees to drive using a hand-held phone.

Motoring organisations have backed the new law.

RAC spokeswoman Rebecca Bell said it was a step forward for road safety.

"We strongly advise motorists not to make or take phone calls, even when they have hands-free equipment in their vehicle," she said.

"A phone call can compromise safe and responsible driving."

Geoff Hoyle, general manager of AA Insurance Services, said many drivers were unaware they would be putting their insurance at risk if they had an accident while breaking the law.

"If you have an accident while jumping a red traffic light, there's a chance the damage to your car won't be covered," he said.

"After December 1 the same will apply to the use of a hand-held mobile."

Drivers have indicated they understand the reasons behind the new regulation.

In a survey carried out for Budget Insurance Services, 87 per cent of drivers agreed that using a mobile phone without a hands free device was dangerous.

MOBILE PHONE USE . . .

The RAC recommends that if you do need to use a phone while in your vehicle that you only do so with a fully fitted car kit and follow these simple guidelines:

Keep call making to a minimum.

Use pre-programmed short-dial numbers wherever possible.

Keep the calls brief and avoid conversations that are likely to be distracting never argue or negotiate on the move.

Explain to the caller that you are driving and may have to break off the conversation at any time and without warning.