More than a fifth of British drivers admit to driving shortly after taking illegal drugs, claims an insurer who is pushing for the introduction of roadside drugs screening devices.

Motorists in the UK are among the worst drug driving offenders in Europe with 21 per cent getting behind the wheel after taking illegal substances and seven per cent having been involved in an accident while impaired by drugs, according to research by More Than.

Worryingly, 38 per cent of drug drivers think their driving is not affected by drugs or that their behaviour is safe.

However, 94 per cent of those surveyed said that they would not drive if they thought they were over the legal blood alcohol limit.

Independent drug impairment expert and consultant to More Than, Dr Rob Tunbridge, commented: "Many people just don't realise the effects that illegal drugs have on their ability to drive and to think straight, and this may be part of the reason why young people in particular continue to drive while impaired by drugs"

More Than is urging the government to speed up the introduction of roadside drug screening, already in use in Sweden, Switzerland, Belgium, Finland, Australia and Germany, where police examine body fluids like saliva or sweat to check for illegal substances.