ASUNCIÓN, Paraguay — At least 75 members of a powerful Brazilian drug cartel escaped from a prison in northern Paraguay through a tunnel on Sunday, pulling off an escape plan that officials had known about for more than a month but were unable to stop.
The breach is the latest and most serious sign that Brazilian cartels, which use Paraguay as a transit point to smuggle arms and drugs into Brazil, have penetrated the security agencies.
“This is a prison break without precedent,” Paraguay’s justice minister, Cecilia Pérez, said on Sunday. “This is the biggest prison break from our facilities.”
Members of the cartel, the First Capital Command, had spent weeks digging the tunnel from their wing of the Pedro Juan Caballero prison, piling dozens of bags of dirt into a cell, according to officials in Paraguay.
On Sunday around 4 a.m., aided by guards at the prison, the cartel members sneaked out, officials said.
The prison is near the Brazilian border, and “by now they’ve probably crossed over to the other side,” Ms. Pérez said. “This is very serious.”
Pedro Juan Caballero has long been regarded as a particularly troubled prison, said Dante Leguizamón, the president of the National Mechanism to Prevent Torture, an independent government agency that monitors conditions in prisons in Paraguay.
“We consider it the prison with the most severe corruption problems,” Mr. Leguizamón said Sunday in an interview. “Considering the fragility of the system as a whole and crowding conditions, this is not a terribly surprising situation.”
According to statistics compiled by the organization, the prison was until recently holding 1,005 inmates, slightly more than double the capacity for which a facility of its size is equipped.
A month ago, Ms. Pérez announced that Paraguay’s government had learned of a plot by the cartel — known as the P.C.C., its initials in Portuguese — to pay guards $80,000 to facilitate the escape of a cartel leader.
Ms. Pérez said on Sunday that it was clear that corrections officials had enabled the plan to be carried out. At least five prison guards have been suspended and are under investigation, she said.
“We are certain that there was a scandalous conspiracy with security guards,” Ms. Pérez said. “They had been working on this for several days.”
Paraguay’s interior minister, Euclides Acevedo, said the government was in a state of “maximum alert” and had dispatched its “best investigators” to the area in an effort to recapture the prisoners.
The government also alerted officials in Brazil, where state and federal law enforcement officials were deployed to the border area to search for the escapees.
“We are working with state officials to prevent criminals who escaped from prison in Paraguay from returning to Brazil,” Brazil’s justice minister, Sérgio Moro, said Sunday afternoon in a statement on Twitter. “If they make it back to Brazil, they will get a one-way ticket to a federal prison.”
The Brazilian drug cartel, which has tens of thousands of members, dominates the cocaine industry in São Paulo. Ms. Pérez said the most senior cartel leader who fled was David Timoteo Ferreira, a Brazilian P.C.C. leader who had been in custody in Paraguay since 2017.
Paraguay’s prison system has long been underfunded, understaffed and prone to corruption. In much of the country, cartel leaders effectively run prisons, which have become hubs where the P.C.C. and other drug trafficking groups plan operations and recruit new members.
After a mutiny at a prison last June in which 10 inmates were killed — and some decapitated — during a clash between rival gangs, Paraguay passed a new law giving the state additional powers to address the system’s shortcomings. It included funding for an additional 500 prison guards and gave the national police and the military the authority to reinforce prison security.
The measures in the emergency law clearly “were not enough,” Ms. Pérez said on Sunday.
Mr. Acevedo said that in Sunday’s case the tunnel may have been built to provide a cover for complicit prison guards. “There’s complicity from people in the inside, and this is a phenomenon that affects all prison facilities,” he said.
Paraguay has long struggled to detain and prosecute powerful drug traffickers as Brazilian cartels have become deeply entrenched in the tiny South American nation.
In November 2018, a prominent Brazilian drug trafficker, Marcelo Pinheiro Veiga, killed a teenage prostitute who had been taken to a special cell designed for him in a heavily secured police station.
Officials believe Mr. Veiga killed her in an effort to prevent his extradition to Brazil, where he faces numerous charges.
Yet shortly afterward, he was deported to Brazil — a step widely regarded as an admission by Paraguay’s government that it felt unable to keep him in custody and bring him to justice for that killing and several other crimes.
Santi Carneri reported from Asunción, and Ernesto Londoño from Rio de Janeiro.