Pope Francis condemned drug traffickers as "dealers of death" yesterday during a visit to a rehabilitation centre in Rio de Janeiro.
The Argentine Pope spoke out about the effects of "chemical dependency" during an encounter with crack cocaine addicts at the city's St Francis of Assisi Hospital.
Earlier, he had prayed at Brazil's most revered Roman Catholic shrine, a huge basilica devoted to the Virgin Mary in the town of Aparecida, between Rio and Sao Paulo.
"How many dealers of death there are that follow the logic of power and money at any cost," the Pope said.
"The scourge of drug-trafficking, that favours violence and sows the seeds of suffering and death, requires of society as a whole an act of courage."
Pope Francis, the first Pontiff from South America, criticised countries in Latin America that had declared the war on drugs could never be won and that some alternative to total prohibition must be found.
"A reduction in the spread and influence of drug addiction will not be achieved by a liberalisation of drug use, as is currently being proposed in various parts of Latin America," he said.
Instead it was necessary to confront the underlying problems of drug use and addiction, including "promoting greater justice" and "educating young people in the values that build up life in society".
Many countries in Latin America, where the decades-long fight against drugs has left tens of thousands of people dead or maimed, have proposed relaxing the blanket prohibition on illegal drugs.
Uruguay has spearheaded the movement, announcing last year plans to legalise sales of marijuana but under strict state controls.
Argentina, the Pope's home country, has moved towards decriminalising personal consumption of some drugs.
Brazil, which is hosting the Pontiff's week-long visit, has also partially decriminalised the personal possession of drugs. Fernando Henrique Cardoso, a former President of Brazil, has called for "an open debate on more humane and efficient drug policies". Costa Rica, Honduras, Mexico and Colombia have also relaxed their attitudes to personal drug use in recent years.
Last year Otto Perez Molina, the Guatemalan President, said that "drug consumption, production and trafficking should be subject to global regulations, which means that drug consumption and production should be legalised, but within certain limits and conditions".