A federal judge has refused a blanket request from the Trump administration for extra time time to reunite migrant children and their parents separated at the US-Mexico border, saying extensions will only granted in cases where there was an “articulable” reason.

Last month, District Judge Dana Sabraw issued an order for the government to reunite up to 3,000 children split from their families as a result of a “zero tolerance” immigration policy that resulted in officials charging anyone apprehended crossing the border illegally. He ordered children under the age of five to be reunited with their parents by July 10, and for all children to be reunited by July 26.

As the government responded to the court order, making use of DNA testing to speed up the process, it appealed for extra time to reunite families. “The Department of Health and Human Services (HHS) anticipates, however, in some instances it will not be able to complete the additional processes within the timelines the court prescribed, particularly with regard to class members who are already not in government custody,” the government’s lawyers wrote last week.

But Mr Sabraw rejected the blanket request for extra time, acknowledging instead, that more time may be justified only in specific cases. The administration said it needed more time to reunite 101 children under 5 years old to ensure the children’s safety and to confirm their parental relationships.

“There’s always going to be tension between a fast release and a safe release,” said Sarah Fabian, a Justice Department lawyer, according to the Associate Press.

On Friday, Mr Sabraw ordered the government to share a list of the 101 children with the American Civil Liberties Union, which successfully sued to force the reunions. The two sides will try to determine over the weekend which cases merit a delay in an effort to present a unified front in court on Monday morning.

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“The government must reunite them,” the judge said. “It must comply with the time frame unless there is an articulable reason.”

The administration has matched 86 parents to 83 children and 16 are not yet matched, Ms Fabian said.

Undocumented immigration across the US-Mexico border Show all 14 1 /14 Undocumented immigration across the US-Mexico border Undocumented immigration across the US-Mexico border Immigrant children, many of whom are separated form their parents, are housed in Texas' tent city Reuters Undocumented immigration across the US-Mexico border A two-year-old Honduran asylum seeker cries as her mother is searched and detained near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Undocumented migrants ride on the top of a freight train referred to as the beast, or La Bestia Getty Undocumented immigration across the US-Mexico border A cage inside a US Customs and Border Protection detention facility in Texas Reuters Undocumented immigration across the US-Mexico border US Border Patrol Academy All new agents must complete a months-long training course at the New Mexico facility before assuming their posts at Border Patrol stations, mostly along the US-Mexico border Getty Undocumented immigration across the US-Mexico border US-Mexico border fence A group of young men walk along the Mexican side of the US-Mexico border fence in a remote area of the Sonoran Desert Getty Undocumented immigration across the US-Mexico border US-Mexico border fence in the US Man looks through US-Mexico border fence into the US in Tijuana, Mexico Getty Undocumented immigration across the US-Mexico border US-Mexico border fence US Border Patrol agent Sal De Leon stands near a section of the US-Mexico border fence while stopping on patrol on in La Joya, Texas Getty Undocumented immigration across the US-Mexico border US Border Patrol Academy US Border Patrol instructor yells at trainees after their initial arrival to the academy Getty Undocumented immigration across the US-Mexico border Memorial service in Guatemala Families attend a memorial service for two boys who were kidnapped and killed in San Juan Sacatepequez, Guatemala. Crime drives emigration from Guatemala to the United States, as families seek refuge from the danger Getty Undocumented immigration across the US-Mexico border Arrests on the border Undocumented immigrants comfort each other after being caught by Border Patrol agents near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Detention holding facility A boy from Honduras watches a movie at a detention facility run by the US Border Patrol Getty Undocumented immigration across the US-Mexico border Mexican farm workers Mexican migrant workers harvest organic parsley at Grant Family Farms in Wellington, Colorado Getty Undocumented immigration across the US-Mexico border Mexican family in Arizona A Mexican immigrant family sits in the living room of their rented home in Tuscon, Arizona. The family that Arizona's new tough immigrant law had created a climate of fear in the immigrant community. Getty

On Thursday, Health and Human Services Secretary Alex Azar told reporters fewer than 3,000 children were believed to have been separated, but that includes children who may have lost parents along the journey, not just parents who were detained at the border.

“HHS knows the identity and location of every minor in the care of our grantees,” said Mr Azar. “And HHS is executing on our mission, even with the constraints handed down by the courts.”