Pope Francis has demonstrated that there are limits to his modernising fervour as he warned against moves to legalise recreational drugs.

"Drug addiction is an evil, and with evil there can be no yielding or compromise," he said at a drug enforcement conference in Rome.

The Argentinian pontiff's comments, in which he insisted that "the problem of drug use is not solved with drugs", came a month after Uruguay become the first country to legalise the production, sale and consumption of cannabis, a move that is being followed closely in other Latin American countries trying to end the violence spawned by the drugs trade.

The pope, who has spoken out against drug use before, said: "To think that harm can be reduced by permitting drug addicts to use narcotics in no way resolves the problem. Attempts, however limited, to legalise so-called recreational drugs, are not only highly questionable from a legislative standpoint, but they fail to produce the desired effects."

On Saturday Francis is due to visit Calabria, home of Italy's powerful 'Ndrangheta mafia, which controls a significant share of the global trade in illegal narcotics. The pope said drug use was "fed by a deplorable commerce which transcends national and continental borders" and was placing increasing numbers of young people at risk of harm.

Several countries and US states have legalised, or are in the process of legalising or decriminalising cannabis in certain circumstances and/or for small amounts. In 2009, Argentina's supreme court declared that criminalised drug possession for personal consumption was unconstitutional and there have been moves to decriminalise it. Recreational use of marijuana has been legalised in Colorado and Washington, while Oregon may vote on the issue this year. The state of New York prepared on Friday to pass measures that should lead to it becoming the 23rd US state to allow medical use of marijuana.

Addressing heads of world anti-drug agencies at the 31st International Drug Enforcement Conference, the pope said: "I would reaffirm what I have stated on another occasion – no to every type of drug use. It is as simple as that … But to say this no, one has to say yes to life, yes to love, yes to others, yes to education, yes to greater job opportunities. If we say yes to all these things, there will be no room for illicit drugs, for alcohol abuse, for other forms of addiction."