* Cocaine market shrinking, but opium cultivation up - UNODC
* Worldwide drugs demand little changed in recent years
* East and West Africa seen vulnerable to drug trafficking
By Fredrik Dahl
VIENNA, March 13 (Reuters) - The global fight against narcotics has suffered serious setbacks, including record opium cultivation in Afghanistan and a surge of trafficking-linked violence in Central America, the U.N. anti-drugs chief said on Thursday.
At the opening of an international meeting on the issue, Yury Fedotov also noted some successes, such as a shrinking cocaine market.
The two-day gathering will review implementation of a 2009 plan of action to combat the drugs problem before a special session of the United Nations General Assembly in 2016, amid a heated debate on the merits of drugs liberalisation.
Fedotov, executive director of the United Nations Office on Drugs and Crime (UNODC), said reductions in the supply and demand for some drugs in one part of the world had been partly offset by increases elsewhere.
"The overall magnitude of drug demand has not substantially changed at the global level," he told the conference, which organisers said drew 1,500 representatives from member states, civil society organisations and other groups.
"We are strongly concerned about the vulnerability of some regions, notably West Africa and East Africa, to illicit drug trafficking," Fedotov said.
There are around 27 million "problem drug users" in the world and about 210,000 narcotics-related deaths a year, a UNODC document prepared for the March 13-14 conference said.
There is disagreement on how to best counter the scourge, with critics questioning the so-called war on drugs and advocating some legalisation to try to undermine criminal gangs that thrive on narcotics trafficking.
In a move that will be closely watched by other nations discussing drug liberalisation, Uruguay's parliament in December approved a bill to legalise and regulate the sale and production of marijuana - the first country to take such a step.
In the United States, Washington and Colorado states recently legalised the sale of cannabis under license, although federal law has not changed.
Fedotov, who said earlier this week that legalisation was not a solution, told the meeting that "dismantling" the provisions of three international drug control conventions would not help protect people's health and welfare.
However, he said: "A public health response to the drug use problem should consider alternatives to penalisation and incarceration of people with use disorders."
Taking stock of developments in recent years, he said the total area under coca bush cultivation fell by 26 percent between 2007 and 2011. Cocaine use in North America, the world's largest market, has fallen sharply, UNODC data show.
"Sustainable reductions have been achieved through successful alternative development programmes," Fedotov said. "We have seen welcome improvements in treatment delivery."
There had also been strengthened international cooperation, with information-sharing and coordination among law agencies.
"And yet there have been serious setbacks," Fedotov said, noting that opium cultivation reached record levels in Afghanistan in 2013. "Drugs from Afghanistan continue to ... create serious challenges in the region and beyond."
Afghanistan supplies about 90 percent of the world's opium, from which heroin is made, and its poppy-driven economy is helping to fuel the 13-year-long war in the country.
Fedotov also said drug trafficking "has triggered a dramatic surge of violence in Central America".
The illicit market for synthetic stimulants is expanding and there is an "alarming increase" in new psychoactive substances, he added. "Cyber technologies are being more broadly used in drug trafficking and related money-laundering activities." (Editing by Alistair Lyon)