* Illicit drugs kill up to 200,000 every year - UNODC chief
* Afghan opium cultivation surges; cocaine production down
* Cannabis use up in North America, lower in parts of Europe (Adds NGO statement, additional quotes, detail from report)
By Fredrik Dahl
VIENNA, June 26 (Reuters) - More Americans are consuming cannabis as their perception of the health risks declines, the U.N. drugs and crime agency said on Thursday, suggesting legalisation may further increase its use among the young.
In a finding that could feed into an international debate on the decriminalisation of marijuana, it said more people around the world, including in North America, were seeking treatment for cannabis-related disorders.
It was still too early to understand the impact of recent legalisation moves in the U.S. states of Washington and Colorado and the South American country of Uruguay, the U.N. Office on Drugs and Crime (UNODC) said in its 2014 World Drug Report.
However, for youth and young adults "more permissive cannabis regulations correlate with decreases in the perceived risk of use", which in turn may affect consumption, the report said.
Research suggests that declining risk perception and increased availability can lead to wider use and to more young people being introduced to the drug, the UNODC said.
Global cannabis use seemed to have decreased, it said, reflecting a decline in some European countries.
"However, in the United States, the lower perceived risk of cannabis use has led to an increase in its use," UNODC said, without specifying what may have caused this change.
Voters in Washington and Colorado in 2012 became the first in the United States to legalize recreational marijuana, but U.S. federal laws still prohibit sales.
Citing statistics from before the new rules took effect, the UNODC said the number of people in the United States aged 12 or more who used cannabis at least once in the previous year rose to 12.1 percent in 2012 from 10.3 percent in 2008.
"WAR ON DRUGS"
Regarding other narcotics, a surge in opium production in Afghanistan - where the area under cultivation jumped by 36 percent in 2013 - was "a setback", while the global availability of cocaine fell as production declined from 2007 to 2012.
Last year, the worldwide output of heroin "rebounded to the high levels witnessed" in 2008 and 2011, UNODC added.
"Up to 200,000 people die every year due to illicit drugs," UNODC executive director Yury Fedotov said in a statement.
In December, Uruguay became the first country to legalize the growing, sale and smoking of marijuana, a pioneering social experiment aimed at wresting the business from criminals that will be closely watched by others debating drug liberalisation.
Critics say legalisation will not only increase consumption but open the door to the use of harder drugs than marijuana.
"Although the general public may perceive cannabis to be the least harmful illicit drug, there has been a noticeable increase in the number of persons seeking treatment for cannabis use disorders over the past decade," the UNODC said.
But with the U.S.-led war on drugs facing mounting criticism, success in Uruguay could fuel legalisation momentum elsewhere.
In a joint statement, a group of non-governmental organisations, including New York-based Open Society Foundations and Release in London, called on governments to put an end to "the expensive and counter-productive" anti-drugs war. (Editing by Raissa Kasolowsky)