Mexico has detained 138,000 migrant children trying to reach the United States under President Enrique Peña Nieto's administration, adopting similar tactics to U.S. President Donald Trump's reviled 'zero-tolerance' immigration policy north of the border: separating children from their parents.
Trump's policy sparked international outrage when it was revealed migrant children were being kept in inhumane conditions in cages, having been forcibly separated from their families.
Of the 138,000 children put in similar detention centers in Mexico, 97 percent are from Central America, mainly Honduras, El Salvador and Guatemala, and 65,000 were traveling alone.
Entering Mexico without documentation is not considered a crime, but migrants face detention during the administrative process leading to deportation.
When caught by immigration authorities they are first sent to one of 46 provisional detention centers, then one of six migrant concentration centers, where children are sometimes separated from their families.
Children younger than eight are generally allowed to remain with their mothers, but older children are held separately in adult detention. Girls traveling alone with their fathers are sent to other facilities to prevent abuse, regardless of age.
Authorities try not to separate families, but various circumstances mean the practice has been commonplace.
"It's a general practice. There are some moments during the day in which they allow them to be together. That's different," Miguel Paz, of the Citizen's Council of the Migration National Institute (CCINM), told BBC Mundo.
"There are moments in some centers in which the whole population is together the whole day. Just in some."
According to Paz, the biggest problem is that in the 17 centers observed by the Citizen's Council, there are no set criteria or standards regarding separation and, as such, authorities act according to individual circumstances.
"They can't go out. They're in permanent confinement conditions," said Paz. "The testimonies are from children and entire families that have been there for four, five or six or more days and didn't know what it was to see daylight, to take some fresh air."
Detained migrants should be kept in detention centers for a couple of hours only during the administrative process, but in reality that process is often prolonged and migrants stay for a week or more.
Liliana Ruvalcaba, from NGO The Life Well, says migrants remain in detention centers from 15 to 30 days on average, depending on their nationality – something migration authorities deny.
Carlos Madrazo, from the Migratory Control and Verification office, says migrants stay in detention centers an average of eight days. During that time, authorities search for better centers for children, such as shelters or civil associations, but many are full.
"If a child or a teenager comes with one of its parents they are not separated. We won't separate families to take them to a shelter outside the center. Family union is preferred," Madrazo told BBC Mundo.
Even those allowed to remain with their parents are often kept in unsuitable conditions. Some centers lack sufficient light, ventilation or daily cleaning supplies. People get sick due to bad sanitary conditions and food. This can lead to serious physical and psychological consequences, especially for children.
The alternatives to detention, however, are often worse. During their long trip to the Mexico-U.S. border, often through dangerous areas perched on top of cargo trains, migrants risk being sexually abused or kidnapped by human traffickers.
Ruvalcaba said: "Some children hand themselves over. They feel vulnerable and without a chance of reaching their destination. We find trafickers making them sell themselves. We find sexual abuses. Children lost on the road and then found by organized crime."