Police stand guard in the parking lot of the municipal jail in Ciudad Juarez (Reuters)
Two hundred and fifty prisons in Mexico - more than half the number in the country - are controlled by drug cartel members who hold the keys to their own cells and who have sometimes led mass breakouts simply by walking through the front gates.
According to a report by Mexico's human rights commission (CNDH), 60 per cent of the country's 430 prisons are "self-governed" by convicts.
Cartel members enjoy a privileged status among the detainees, said CNDH president, Raúl Plascencia Villanueva.
Gang affiliates lead a life of luxury behind bars, claimed the report, with alcohol, weapons, drugs, baseball bats, mobile phones, call-girls and fighting cocks easily available for members of the Zetas, Sinaloa and other powerful drug gangs.
Such lawlessness has resulted in 352 deaths and 45 injuries among inmates in the last year alone as inter-gang violence and score-settling erupted behind prisons walls.
Since 2010, 521 prisoners have escaped in 14 incidents - an average of 40 prisoners per breakout.
Earlier in September, 130 convicts escaped from the Piedras Negras penitentiary in Coahuila, near the US border, by simply walking through the front gates as prison guards turned a blind eye.
Villanueva reported that CNDH representatives conducting the survey were not allowed into Piedras Negras because of the reigning "lawlessness".
Police corruption is a widespread problem in Mexico. Thirty-five police officers were arrested recently by the Mexican Navy for their links with the Zetas drug cartels.
According to the CNDH report the chaos in the prison system is partly due to overcrowding.
Total capacity stands at 190,000 but the prisoner population is 240,000.
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The prison of Apodaca on the outskirts of Monterrey (Reuters)
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