Doctors told drivers today that using a mobile phone, even a hands-free type, in the car could damage your health or kill you.
Scientists are still investigating the potential hazards of mobile phones and possible links to cancer, but one thing they agree on is that using a phone while driving is dangerous and increases the risk of an accident.
"There is strong experimental evidence that engaging in mobile phone conversations can impair ability to react to potentially hazardous situations," said Dr Vivienne Nathanson of the British Medical Association (BMA).
The BMA has published a new report on the issue, which summarises existing knowledge about mobile phones and public health.
The report, entitled "Mobile Phones and Health", said evidence indicates that using a hands-free kit is just as dangerous as using a hand-held set.
It said there are still large gaps in research about the potential dangers of electromagnetic fields emitted from the phones and urged users to adopt a cautionary approach.
But all the main professional bodies have called for more research to be done, since the possibility radio-frequency radiation may cause adverse effects cannot be ruled out on the currently available data, Dr Nathanson said.
The World Health Organisation is researching the potential dangers of mobile phones.