Warnings have been issued after a survey revealed that many of the UK's top bosses admit to working while driving.
Some 20% of business owners and senior managers have taken part in conference calls while at the wheel, workspace provider Regus discovered.
And 75% of these say they often make calls to customers and work colleagues when they should be concentrating solely on the road.
From the survey sample of 1,800, one in 10 said they had used their phone to record verbal notes while driving; and two in five said they had held important business discussions - equivalent to sitting in on a meeting - while at the wheel of their vehicle.
RAC spokesman Simon Williams said: "As a nation we are very much wedded to our mobile phones, but everything has to change when at the wheel of a vehicle. While it's legal to use a mobile phone hands-free while driving the nature of some calls can make it harder to focus on the task of driving and that's where a common sense decision is required.
"For example, taking part in an important conference call might be far more difficult as you are not necessarily in control of the conversation and therefore might find it difficult to stop talking when you need to focus on making a complicated manoeuvre or a decision on which road to take."
Regus UK chief executive John Spencer said that the distractions of working while driving are comparable to the effects of drink-driving in terms of concentration levels and decision making.
He added that the onus is on companies to better manage their mobile staff and offer better training in relation to driving/work balance as well as making provision for drop-off workspaces that allow employees to conduct their business in a safer environment.
Copyright Press Association 2014