The UN's Commission on Narcotic Drugs (CND) is meeting in Vienna to review the effectiveness of drug control over the past decade.
The conference will also set the agenda for international drugs policies for the next 10 years.
Critics say the policies are flawed, contributing to organised crime, violence and instability in the developing world.
But the UN Office on Drugs and Crime (UNODC) says there has been progress.
It says the number of drug users, about 5% of the world's population, has stabilized over the past few years.
An EU report presented before the meeting suggested that international policies had failed to reduce the global drug problem over the past decade.
Critics say the UN's narcotics policies have fuelled organised crime
The head of UNODC, Antonio Maria Costa, acknowledged that drug control policies had, as an unintended consequence, led the growth of organized crime.
Mr Costa said the focus of discussions would be on organised crime and the fact that much of it generated by the narcotics control regime.
"The important answer I am expecting from member states is what are they planning to do to control mafia and thus to control crime, not only because of the violent dimension, but also because organised crime is starting to undermine a number of smaller countries," he said.
The complexity of the drugs issue - which spans health policy, law enforcement and international relations - means no two countries tackle the problem in the same way.
Some European and Latin American countries want to put more emphasis on public education and the treatment of addicts, rather than criminalising addicts and drug farmers in the developing world. But other countries, including the United States and Russia, favour a more traditional approach to the problem of drugs.
By BBC News, 11 March 2009
Original Source: http://news.bbc.co.uk/2/hi/europe/7936605.stm