Up to a third of all road traffic accidents nationally - about 20 fatalities and 250 serious injuries every week - involve somebody who was at work at the time.

Now David Egan, health and safety law expert and partner with national law firm Shoosmiths, is warning employers and managers in the West Midlands they are legally bound to ensure the health and safety of all employees while they are on the road in the course of work.

Health and safety law applies to on-the-road work activities, and employers are required to ensure that both their workforce and others are not at risk from their employees' driving activities.

Mr Egan said: "This can best be effectively managed if it is integrated into health and safety policy. There is a legal responsibility to undertake risk assessments, and when evaluating risk, consideration should be given to the driver, vehicle and the journey.

"Risk assessments for any work-related driving activity should follow the same principles as risk assessments for any other work activity.

"More importantly, employers should bear in mind that failure to properly manage work-related road safety is more likely to endanger other people than a failure to properly manage risks in the workplace."

Mr Egan said that while employers are not responsible for their staff when they are commuting from their home to their normal place of work, they are when going to another site or driving on business directly from home.

"There was a case earlier this year when a road haulage director was jailed for seven years after one of his lorry drivers fell asleep at the wheel and was involved in a fatal accident. It was found he had encouraged and enabled his drivers to work dangerously long hours."