VIENNA (Reuters) – Motorists under the influence of drugs are a growing threat on US roads, while the number who drink and drive has fallen thanks to education and law enforcement, a top US drug control official said yesterday.

The United States is calling for discussions at United Nations level to tackle “drugged driving” and says it wants to collect data to gauge the scale of the problem among public sector drivers and commercial truckers.

“If you think about driving on an American road on a Friday or Saturday evening about 16 per cent of the vehicles – one in six of the cars – (the driver) will be under the influence of an illicit or licit drug,” Gil Kerlikowske, director of the US Office of National Drug Control Policy, said.

“Drugged driving is a significant problem.” he told reporters at a week-long UN drug policy review meeting.

Kerlikowske, a former Seattle police chief, said figures showed one of the main problems was with people using marijuana and then getting behind the wheel.

But he said in a statement to the UN Commission on Narcotic Drugs (CND) meeting in Vienna that both illicit drugs and prescription or other pharmaceutical drugs could cause severe problems on the road.

He described the way in which “drugged driving” hampered judgment, reaction time, driving skills and memory and called for the issue to be debated as an official topic at the next CND meeting in 2011.