WASHINGTON — A Mexican regulation has stopped the US from quickly turning away migrant households at one of many busiest sections of the southwestern border, forcing brokers to renew releasing households into the nation, based on three Biden administration officers.

The Trump administration began turning back migrants getting into the US in March, citing the specter of the coronavirus, and the emergency rule successfully sealed the border from asylum seekers. However due to a regulation Mexico handed in November that prohibits the detention of immigrant youngsters and households, the nation has stopped accepting such households from South Texas, an space usually prone to unlawful crossings, officers mentioned.

The latest shift has alarmed officers on the Division of Homeland Safety and presents a right away problem to the Biden administration. Homeland safety officers have mentioned the emergency rule was mandatory to forestall the coronavirus from spreading in detention services alongside the border, even because it prevented susceptible households from having their asylum claims heard. An rising variety of households have been held in latest weeks in such services within the Rio Grande Valley, in addition to in Del Rio, Texas, officers mentioned.

Stephanie Malin, a spokeswoman for Customs and Border Safety, mentioned due to pandemic precautions and social distancing tips, some services had reached full “protected holding capability.”

“C.B.P. takes very significantly the protection and well-being of its work drive and people they encounter, and we’re taking much more precautions as a result of Covid-19,” Ms. Malin mentioned. “As they all the time have, the variety of people crossing the border continues to fluctuate, and we proceed to adapt accordingly.” She mentioned the company was working with organizations in the neighborhood when releasing migrants into the general public.

America has expelled greater than 390,000 migrants again to Mexico or their dwelling international locations since March. The rule lowered the variety of migrants detained on the U.S. facet of the border, but it surely additionally sent Central American families scrambling at times after they realized that their youngsters had been delivered to Mexico, a violation of worldwide agreements. And whereas the coverage was a vital piece of the Trump administration’s makes an attempt to shut the border to migrants, the rule additionally had the unintended effect of giving migrants extra possibilities to enter illegally.

Customs and Border Safety recorded greater than 73,000 crossings in December, a rise from the greater than 40,000 in July. Brokers detained greater than 40,000 migrants in December 2019.

The Mexican regulation, which took impact in January, doesn’t apply to the complete border, officers mentioned. American border brokers are nonetheless turning again single adults, and in locations like Arizona, households, as effectively, officers mentioned. It’s unclear how the regulation will have an effect on different elements of the border.

A spokesman for the International Ministry in Mexico declined to touch upon whether or not it had stopped accepting migrant households, saying solely that the US continued to have the pandemic emergency rule in place.

However the Biden administration has been unable to return migrant households to Reynosa, Mexico, a change that was first reported by The Washington Post. The shift has elicited concern at Customs and Border Safety of a possible rise of crossings by households to the neighboring Rio Grande Valley. Border crossings in recent times have been fueled largely by Central American households fleeing persecution, violence and poverty.

The Division of Homeland Safety is at present constructing a tent facility in Donna, Texas, to accommodate migrants, however an administration official mentioned that was unrelated to the regulation in Mexico. Customs and Border Safety mentioned in November it might shut the primary detention facility in McAllen for renovations.

President Biden campaigned on restoring asylum on the southwestern border and signed an executive order this week directing the administration to assessment rolling again President Donald J. Trump’s restrictionist insurance policies.

The brand new administration has not detailed publicly when the pandemic emergency rule could be lifted. After a federal judge in the District of Columbia lifted a block on the rule, which prevented the US from turning away unaccompanied migrant youngsters, the White Home mentioned it might use its discretion in deciding when to use the coverage.

Mr. Biden said in December that his administration would take a cautious method to reversing Trump-era insurance policies to keep away from a surge on the border.

His immigration plan concerned relying extra on packages that monitor migrants after they’re launched into the US to make sure they present up for immigration courtroom and fewer on detaining them.

Mexico, for its half, drew reward for enacting restrictions on who it detained.

“Mexico is making a decisive step to finish immigration detention for youngsters and we’re inspired by this promising growth,” mentioned Gillian Triggs, the assistant excessive commissioner for the United Nations Excessive Commissioner for Refugees.

Whereas high officers within the Trump administration argued its emergency rule was solely an try to forestall the unfold of the coronavirus, Mr. Trump’s White Home tried to use the policy to further his goals of curbing unlawful immigration.

Kirk Semple contributed reporting from Mexico Metropolis.