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

Cars run on the I-95 highway in Miami in this May 15, 2007 file photo. REUTERS/Carlos Barria

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 percent 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 U.S. Office of National Drug Control Policy, said.

“Drugged driving is a significant problem.” he told reporters at a week-long U.N. 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 U.N. 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.

He also said the United States’ new drug control strategy, to be published in several weeks, will focus more efforts on prevention and treatment of drug abuse while continuing to clamp down on drug trafficking domestically and internationally.

In a separate briefing Kerlikowske’s Russian counterpart praised bilateral anti-drug efforts under the administration of U.S. President Barack Obama, particularly in Afghanistan.

“We can say (joint) activity has been intensified (now),” Victor Ivanov, head of the Russian Anti-Narcotics Service told journalists. Russia is the world’s largest heroin consumer.

He said the two countries had agreed to conduct operations on certain facilities in Afghanistan, producer of over 90 percent of the world’s opium, which fuels a $65 billion illegal market and helps fund the insurgent Taliban.

Ivanov said Russian and U.S. authorities had also exchanged names of people working in the drug trade in Afghanistan that they wanted to target.