The global war on drugs has "failed" according to a new report by a group of politicians and former world leaders.
The Global Commission on Drug Policy report calls for the legalisation of some drugs and an end to the criminalisation of drug users.
The panel includes former UN Secretary General Kofi Annan, the former leaders of Mexico, Colombia and Brazil, and the entrepreneur Sir Richard Branson.
The US and Mexican governments have rejected the findings as misguided.
The Global Commission's 24-page report argues that anti-drug policy has failed by fuelling organised crime, costing taxpayers millions of dollars and causing thousands of deaths.
It cites UN estimates that opiate use increased 35% worldwide from 1998 to 2008, cocaine by 27%, and cannabis by 8.5%.
The 19-member commission includes Mexico's former President Ernesto Zedillo, Brazil's ex-President Fernando Henrique Cardoso and former Colombian President Cesar Gaviria, as well as the former US Federal Reserve chairman Paul Volcker and the current Prime Minister of Greece George Papandreou.
The panel also features prominent Latin American writers Carlos Fuentes and Mario Vargas Llosa, the EU's former foreign policy chief Javier Solana, and George Schultz, a former US secretary of state.
'No harm to others'
The authors criticise governments who claim the current war on drugs is effective.
"Political leaders and public figures should have the courage to articulate publicly what many of them acknowledge privately: that the evidence overwhelmingly demonstrates that repressive strategies will not solve the drug problem, and that the war on drugs has not, and cannot, be won," the report said.
Instead of punishing users who the report says "do no harm to others," the commission argues that governments should end criminalisation of drug use, experiment with legal models that would undermine organised crime syndicates and offer health and treatment services for drug-users.
It calls for drug policies based on methods empirically proven to reduce crime and promote economic and social development.
The commission is especially critical of the US, saying it must abandon anti-crime approaches to drug policy and adopt strategies rooted in healthcare and human rights.
"We hope this country (the US) at least starts to think there are alternatives," said former Colombian President Cesar Gaviria.
"We don't see the US evolving in a way that is compatible with our (countries') long-term interests."
The office of White House drug tsar Gil Kerlikowske rejected the panel's recommendations.
"Drug addiction is a disease that can be successfully prevented and treated," said a spokesman for the Office of National Drug Control Policy.
"Making drugs more available - as this report suggests - will make it harder to keep our communities healthy and safe."
The government of Mexico, where more than 34,000 people have died in drug-related violence since a crackdown on the cartels began in December 2006, was also critical.
Legalisation would be an "insufficient and inefficient" step given the international nature of the illegal drugs trade, said National Security spokesman Alejandro Poire.
"Legalisation won't stop organised crime, nor its rivalries and violence," he said.
"To think organised crime in Mexico means drug-trafficking overlooks the other crimes committed such as kidnapping, extortion and robbery."