Speaking before a crowd of 6,000 at a drug treatment center, Benedict urged "the drug-dealers to reflect on the grave harm they are inflicting on countless young people and on adults from every level of society."

Brazil is the second-largest consumer of cocaine after the United States, according to the US State Department, and big cities across Latin America's largest nation are plagued by drug violence.

Driven by gangs that control street-corner dealing, the problem is particularly acute in the teeming slums of Rio de Janeiro, where gangs lure children into lives of violence and engage in near-daily shootouts with police that kill innocent bystanders.

"Human dignity cannot be trampled upon in this way," the pope said.

The treatment center where the pope spoke was founded by a Franciscan friar and claims an 80 percent success rate, giving addicts spiritual guidance as they milk cows, tend apple orchards and work as beekeepers.

It is just a short distance away from the shrine city of Aparecida, where Benedict on Sunday will open a conference of Latin American and Caribbean bishops aimed at finding ways to reverse the erosion of the church in the region.

Addicts who listened to the pontiff said his visit was important because Brazilian drug users are often ostracized and left to beg on the streets for drug money.

"We are excluded from society, but we are the ones the pope is coming to see," said Diego Cleto, a 19-year-old who started taking drugs at age 13.

The Garatingueta treatment center in a remote hilly region at the end of a dirt road was founded by Friar Hanz Stapel in 1983. There are now 31 similar farm/treatment centers in Brazil and 10 more in countries such as Russia, Mexico and Mozambique.

Before traveling from Sao Paulo Friday night to the hallowed Catholic religious site of Aparecida, Benedict lamented "difficult times for the church" in Brazil amid "aggressive proselytizing" by born-again Protestant congregations.