SAN DIEGO (Reuters) - The U.S. government must provide a list by Saturday evening of the estimated 100 children under the age of 5 who were separated from their parents when entering the United States, a federal judge ordered on Friday.

U.S. Judge Dana Sabraw also ordered the government to explain by Saturday its expectation for reuniting each of those children with their parents by the end of Tuesday.

Sabraw last month issued the reunification order, which also set a July 26 deadline for more than 2,000 children to be reunited.

The U.S. government attorneys said they may fail to meet those deadlines due to delays in confirming family relationships, but Sabraw declined to extend them without more information.

“What I’m contemplating is the government provides a list to plaintiffs counsel by tomorrow 5 p.m. (PDT, midnight GMT) with the identities of the children,” said Sabraw.

He also asked the government to provide the American Civil Liberties Union, which brought the class action case, with expectations for meeting the deadline for each of the children on the list.

The judge scheduled a status conference for Monday at 10 a.m. PDT, and he said he hopes the government and ACLU can reach agreement about any need to extend the reunification deadline.

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The government said in court documents that it was particularly struggling to connect children with parents who were released from detention.

An ACLU attorney, Lee Gelernt, said organizations would jump at the chance to help connect the parents with the children.

“We have been deluged by thousands of doctors, lawyers and people who want to help,” Gelernt said after the hearing. “The outpouring is incredible. Every one is feeling we should not make these children pawns.”

Gelernt criticized the government at the hearing for presenting parents a form that suggests the only way to get their child back is to give up their asylum claim. “We believe there is some coercion going on, whether intended or not,” he told the judge. The separations have sparked a fierce outcry and numerous protests, part of a political firestorm over U.S. President Donald Trump’s “zero tolerance” immigration policy and beefed-up efforts to deter illegal U.S. entry.

But the administration reversed course last month after a groundswell of global opposition and said it would keep families together if possible.

Sabraw also ordered last month that parents have phone contact with their children by Friday.

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All parents in the custody of U.S. Immigration and Customs Enforcement, and who are known to have children aged below 5, had phone contact with them, according to a court filing by Robert Guadian, an ICE official.

Guadian also said children under 5 are detained in 23 facilities across 13 states. ICE has moved 23 parents on commercial flights to be closer to such children in anticipation of reuniting them, according to Guadian.

On Thursday, U.S. Secretary of Health and Human Services Alex Azar told reporters “under 3,000” children are now under HHS care, which includes the 100 under the age of 5.

The government, in a court filing overnight, said the process could further be delayed by steps that were required before parents could be reconnected with their children.

Government agencies are deploying field teams to swab cheeks of children and adults in government custody and using outside laboratories for DNA testing to verify family members, according to the government’s court papers.

In addition to DNA testing to verify parentage, the government said it would need to perform a criminal history check, and has reviewed 300 adults with about 1,400 more to go.