The government is to conduct research into the effects of driving under the influence of drugs, after reports suggest a sharp rise in accident victims who had taken illegal substances.

Scientists at the Transport Research Laboratory, in Berkshire, are testing the performance of drivers before and after taking cannabis.

The research was ordered after a three-year research programme showed one in six road accident victims had traces of cannabis or other illegal drugs in their blood.

A similar survey 10 years ago gave a result of just one in 20.

The move comes as an RAC report shows young drivers are twice as likely to have been driven by someone high on drugs than by someone over the drink-drive limit.

The results of the lab tests are to be released in the next three months.

They are expected to be used, along with improved testing technology, to bring in compulsory roadside tests for drug use, in the same way breathalysers are used to detect drink drivers.

Death toll

Commenting on the findings, RAC group managing director Graeme Potts said: "It is extremely worrying that the use of banned drugs and driving has grown so rapidly."

The organistation also warned that some over-the-counter and prescription drugs can impair driving ability.

It said it wanted a "traffic light" warning system for drugs - with green for those safe to take and drive, amber for caution and red signalling severe adverse effects which would dangerously impair driving.

It is estimated that about 88,000 drivers a year escape prosecution for drug-driving because of the absence of roadside testing.

Experts believe that at least 4,500 deaths and 135,000 serious injuries are caused in Europe each year by drug-driving