The study has been published in the Traffic Injury Prevention Journal, was carried out by scientists from the University of Barcelona and a number of Australian universities and compared the effects of using a phone while driving with the effects of alcohol using a driving simulator.

The 12 volunteers were measured on their reaction times whilst keeping up a steady position on the simulator at speeds of up to 80km/h (50mph).

Results showed that road skills dropped by an equal amount for those who were a quarter over the alcohol limit for driving and those who used their phone to receive or send text messages.

Those having a simple conversation on a hands-free kit had similar reactions to a blood-alcohol level of 0.04g or 40 milligrames of alcohol in 100 litres of blood – under the UK drink-drive limit – but more complicated conversations were equivalent to 0.07g – close to the limit and therefore representing an increased risk.

Sumie Leung Shuk Man, co-author of the study, said: ‘The use of hands-free devices could also put drivers at risk. Although they should be allowed, they require more research to determine how they should be regulated.’