The government of Colombia pushed on Saturday for the most far-reaching change to policy on drugs since US president Richard Nixon declared war on narcotics four decades ago.

Hosting the sixth Summit of the Americas, for which 33 leaders of the hemisphere's 35 nations – including President Barack Obama – have assembled in Cartagena, President Juan Manuel Santos proposed the establishment of a taskforce of experts, economists and academics to analyse the realities of global drug addiction, trafficking and profiteering, with a view to a complete overhaul of strategy.

Santos's close aide and ambassador to London, Mauricio Rodríguez, said the outcome "could mean anything from blanket legalisation to a new and different war on drugs. We just do not know until we have the data, investigate every option with open minds, and have the full picture drawn up by experts who know the terrain, and are not motivated by interests, ideology or emotion. Whatever it is, it must be real change, based upon new paradigms.

He added: "Why is Colombia leading this? Because we learned the hard way, and we have the moral authority. In the 1980s we failed to face the reality, and as a result our society was taken to the brink and almost destroyed by violence and the drug cartels. And we do not want other places, in Central America or Africa, to go through the pain we went through. They – and all of us – have to act fast, because the many-headed monster grows very fast and destroys very fast.

"For so many years it has been easy for politicians to blame drug-producing nations like Colombia for poisoning their lovely kids. And the result has been a stigma on Colombia. But that game – that farce – is now over. We are not pointing any fingers, and Colombia will not act unilaterally. But we are saying that there is a shared responsibility between consuming and producing nations who must all now co-operate on a global scale to stop the scourge of drugs in our societies."

Rodríguez cited a recent debate broadcast on Google and YouTube by the London-based organisation Intelligence Squared as having "demonstrated why we have got nowhere: emotion, insults, celebrities".

He said the taskforce urged by the Colombians "needs to be made up of real experts: people who know the realities of drugs, the sociology and anthropology of drugs, the economics of drugs and the trafficking and laundering routes – and people who know what drugs do on the ground".

The body would "look at the social issues, the reasons why people take drugs: poverty, social breakdown, abuse and dysfunction".

Talking about the Colombian city of Medellín, once the drug murder capital of the world and now regenerated, Rodríguez said: "We need to look at the kinds of social urbanism that we applied to Medellín, which can isolate the criminals and give people other things to do with their lives, rather than resort to drugs."

Last week Colombia announced the results of research which shows that only 5% of profits from Colombia's drug trade remain in the country. Hhundreds of billions of dollars of drug money finds its way, said Rodríguez, into "the distribution networks in the consuming countries, and the international banking system".

The "real value of the drugs", said the ambassador, "is not added in the countries of production, but once the product is moved – mainly to the US and Europe. And it is therefore clear that more must be done to fight international money-laundering of drug profits by the banking community."