(CNN) — The Trump administration said Friday that it may need more time to reunite the immigrant families it separated.

The Department of Justice informed a federal judge in San Diego that the administration is in compliance with the judge’s order requiring the end of family separations at the US-Mexico border, except under prescribed conditions, such as the safety of the child, and ensuring communication with separated parents and children as of Friday.

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But ahead of a hearing in federal district court Friday afternoon, the Justice Department laid out certain challenges in meeting the reunification deadlines of July 10 for children under age 5 and July 26 for children over 5 and said it may request more time.

The Department of Health and Human Services Secretary Alex Azar released a new estimate Thursday that fewer than 3,000 children remained in their care likely who were separated from their parents, but he said analysis was ongoing and he could not provide a more precise figure. The high number of families separated have been a result of the Trump administration’s “zero-tolerance” policy, which criminally prosecutes any adult crossing the southern border illegally.

Health and Human Services is using DNA testing to confirm parentage, which can take time, the government said in a court filing Friday morning.

The Justice Department also asked if the court will permit reunifications outside of the ordered timelines “in cases where parentage cannot be confirmed quickly.”

The government said it is willing to propose an alternative timeline.

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Health and Human Services must determine that a “parent is not ‘unfit or presents a danger to the child,'” which means the agency must also have “an independent finding that the individual has not engaged in any activity that would indicate a potential risk to the child,” before reunification.

This process can be slowed down if the judge’s court order is interpreted to mean Immigration and Customs Enforcement must release parents from detention by compliance deadlines and the Justice Department argued that “such release might slow reunification.

In the court filing, the Justice Department sought clarification on whether they have to reunite migrant kids with parents who were already deported and appeared to argue that would be too difficult and time consuming. The department’s attorneys have also asked whether the families separated should be counted from the May “zero tolerance” policy or dated to the beginning of the lawsuit, March 9.

The filing contained a description of steps undertaken by Health and Human Services to comply with the court order including deploying 115 additional personnel to the field, and contracting with 100 reunification managers who are deploying Friday and Saturday.

The agency said it has expedited its existing process for reunification.

Health and Human Services also claimed in the court documents that it “knows the names and locations of all children who are in (Office of Refugee Resettlement) care and custody at all times because ORR maintains that data in its online case management portal,” but says the portal was not designed to include certain details regarding the parents which Department of Homeland Security may hold or the parent may have.

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