Draft guidance published by the General Medical Council (GMC) makes it mandatory for doctors to report any motorist to the Driver and Vehicle Licensing Agency (DVLA) if they fear they could cause a crash because of poor eyesight or could be at risk of suffering a fit or a heart attack.
Previously the GMC's guidance did not make it mandatory for doctors to tell the DVLA if they thought a patient was unfit to drive, only if they believed a motorist was potentially dangerous.
The draft guidance states: "If you do not manage to persuade the patient to stop driving, or you consider that they are continuing to drive against your advice, you should contact the DVLA immediately and disclose any relevant medical information, in confidence, to the medical adviser."
The guidance adds that doctors should tell their patients that they have done so.
The move is not just to protect the public from accidents but also to save doctors from being sued for negligence if a patient who should not have been allowed on the road crashes their car.
It comes amid growing concern about the number of elderly drivers in Britain.
The British Medical Association (BMA), the doctors' professional body, currently only advises medics to consider reporting a motorist but its guidance makes it clear this is for their own benefit as well as that of other road users.
The BMA is also likely to change its guidance if the GMC draft rules are agreed when the consultation finishes in November.
The GMC guidance can be found here. The consultation ends on 28 November 2008 and the results will be published in May 2009.