LOS ANGELES — The federal judge overseeing the court-ordered reunification of the 2,551 migrant children separated from their parents at the border blasted the Trump administration Friday for lacking a plan to reunify the remaining 572 children in its custody with their parents and the slow pace of progress.

In a Thursday night status report filing, the Trump administration said only 13 of the parents had been located by the American Civil Liberties Union, which U.S. District Judge Dana Sabraw of the Southern District of California called "unacceptable at this point."

The parents of 410 children are currently outside of the United States, likely having been deported before reunification, according to the court filing.

The Trump administration had proposed the ACLU take the lead in locating and identifying what the judge had called "missing parents" of children still in government custody. Sabraw said that plan was not acceptable and placed that responsibility squarely on the government.

"Many of these parents were removed from the country without their child," Sabraw said. "All of this is the result of the government's separation and then inability and failure to track and reunite. And the reality is that for every parent who is not located there will be a permanently orphaned child. And that is 100 percent the responsibility of the administration."

The judge said he would soon issue an order to compel the government to provide information on still separated families to the ACLU no later than Aug. 10.

A man holds his daughter by the hand after picking her and his wife up at the Air Force base in Guatemala City after they were deported from the U.S. on July 10, 2018. Orlando Estrada / AFP - Getty Images file

Sabraw said the government must identify a person or team to oversee the remaining reunification process, potentially from the State Department or the Department of Health and Human Services, and produce a plan as to how reunification would be accomplished.

Sabraw also said he would order the ACLU to organize a steering committee to provide a plan as to how it would use the information provided by the government to locate the remaining parents.

ACLU attorney Lee Gelernt said the judge was extremely clear in stating that parents with minor criminal charges could be excluded only from the pool that was required to be reunited by his deadline and should not be permanently ineligible for reunification.

Jacob Soboroff reported from Los Angeles, and Julia Ainsley from Washington.