MEXICO CITY —  Detention centers at five times capacity. Migrants held on sports fields. Not enough medicine or health-care workers to go around.

In the weeks since Mexico signed a pact with the United States to stop migration, conditions in detention centers and shelters have deteriorated dramatically, according to diplomats and human rights officials who have visited the facilities.

“It is an absolute indignity,” said Ranger Morales, Guatemala’s consul in the southern state of Chiapas, the first stop for the majority of Central Americans entering Mexico. “The citizens of my country are not receiving medical attention. There are sick children. The conditions are the worst I’ve seen.”

Mexico has historically devoted far fewer resources to immigration enforcement than the United States. But in a bid to avoid the U.S. tariffs threatened by President Trump, the country has dispatched its new National Guard to its southern border and added highway checkpoints to stop the flow of Central Americans traveling northward to the United States. Officials are working to meet a 45-day deadline to stem the tide.

All that has led to a surge in the number of apprehended migrants, with hardly any shelters or centers to hold them. Mexico’s National Human Rights Commission says multiple shelters and detention centers are now at several times capacity.

“With that kind of overpopulation, you can’t treat people with dignity,” said Edgar Corzo Sosa, who as inspector general of the human rights council visits the centers weekly. “The concern is that the operations will only increase, and with them the number of detained migrants.”

In the Chiapas city of Tapachula, officials converted an open-air fairground into a makeshift shelter. Detainees there staged a protest last week.

“Help me. Help me with my son,” one woman cried through the fence. “He is sick. My son is dying.”

Officials said they were closing the center.

The conditions have cast doubt on Mexico’s ability to fulfill its promise to the Trump administration — to swiftly end migration to the United States — while ensuring the humane treatment of the migrants. The situation is also putting strains on Mexico’s  relations with its Central American neighbors, whose diplomats are now expressing concern about the way their countries’ citizens are being treated.

Mexico’s foreign minister, Marcelo Ebrard, acknowledged last month that migration facilities near Mexico’s southern border were “well below standards.” The country’s deputy foreign minister for Latin America, Maximiliano Reyes, has been tasked with improving and expanding some shelters.

But with the number of detained migrants rising so quickly, fixes are coming mostly on the fly. In the city of Tuxtla Gutierrez, after 400 migrants were detained in a facility with a capacity of 80, officials agreed to move some to a nearby boxing arena, which angered human rights officials. 

Mexico has detained 99,203 migrants this year and deported 71,110 of them, according to its immigration agency. That’s more than were detained in all of 2017. In June alone, Mexico detained 29,153 migrants, the largest number in any single month in recent Mexican history.

In northern Mexico, to which the United States is increasingly returning asylum seekers to await their court hearings — another part of the migration deal — capacity has also become a major problem.

U.S. Customs and Border Protection officials have told the municipal government of Nuevo Laredo that they will soon begin sending asylum seekers to wait in the city.

But city manager Raul Cardenas said that Nuevo Laredo’s shelters were already overflowing and that officials would now be forced to consider sending migrants to a local baseball field or basketball court.

Under international law, when Mexico detains a foreign national in its territory, it is obliged to inform that person’s consulate. But Morales said Mexico detained 59 Guatemalans in southern Mexico without informing him or any other Guatemalan officials.

He met them on a routine visit to a detention center in Comitan, where he described the conditions as “miserable.”

“They are generating a horrible crisis,” Morales said. “And what’s worse is that they are not always telling us when they detain our citizens.” 

Guatemalan officials are not the only ones angered. A 19-year-old Salvadoran woman was fatally shot after the truck carrying her and other migrants sped through an immigration checkpoint in the state of Veracruz. Witnesses and survivors blamed police. The government is investigating.

Salvadoran officials have been careful not to speak out publicly during the investigation. But privately, they have expressed deep concerns about the possibility that more migrants could be shot and killed by Mexican police in the midst of the crackdown and as the National Guard’s deployment grows.

“Even though in Mexico, migration is not a crime, migrants are being treated like criminals and feel that way,” said a Salvadoran official who has worked with Mexico on migration issues. The official was not authorized to talk publicly and spoke on the condition of anonymity. “With the deadline for Mexico to comply with the agreement with the U.S.,” the official said, “the measures could intensify and generate more victims both outside and inside the detention centers.”

Under President Andrés Manuel López Obrador, Mexico’s government has said it will strike a balance between enforcing immigration laws and respecting the rights of migrants. López Obrador has said that any migrant in need of refuge can apply for a humanitarian visa to live and work in Mexico.

But migrants are often detained for days or weeks while they pursue those visas, often more than the 15-day limit mandated by Mexican law, according to Sosa, the human rights official. They are typically released in southern Mexico, with their visas pending. But the visa process — particularly for humanitarian visas — faces enormous backlogs. 

Migrants can wait for months, without the guarantee of shelter or food. Hundreds are now sleeping on the streets of Tapachula.