Employers should carefully check the driving licences of foreign staff who are eligible for company cars in the UK or they may risk prosecution if these are subsequently found to be invalid.

Many foreign drivers are thought to be on the roads illegally because employers have no robust procedures to check the numerous varieties of overseas licences.

According to AA Business Services, several drivers have been caught with invalid licences, including a Croatian who had been behind the wheel for 15 years without a valid licence.

Paul Holmes, head of risk management, says: "This is just the tip of a very worrying iceberg. If you are a fleet manager how do you know if the licence you have been provided with is legal? It may look bona fide but you have no immediate way of telling."

At worst, employers which do not check that staff have the necessary documentation could be prosecuted by the Health & Safety Executive if a driver without a valid licence is involved in an accident causing death or serious injury.

Colin Tourick, director of fleet consultancy Colin Tourick and Associates, added: "[Fleet managers] should talk to the relevant embassy and ask what a valid licence looks like. Take, for example, [UK] licences - they are in two parts and a driver can hand over what looks like a valid licence without anyone knowing that they have endorsements on the other half."