WASHINGTON (AP) — Tens of thousands of young families caught crossing the border illegally earlier this year subsequently failed to meet with federal immigration agents, as they were instructed, the Homeland Security Department has acknowledged privately.

An official with U.S. Immigration and Customs Enforcement revealed that about 70 percent of immigrant families the Obama administration had released into the U.S. never showed up weeks later for follow up appointments.

The ICE official made the disclosure in a confidential meeting at its Washington headquarters with immigration advocates participating in a federal working group on detention and enforcement policies. The Associated Press obtained an audio recording of Wednesday’s meeting and separately interviewed participants.

On the recording obtained by the AP, the government did not specify the total number of families released into the U.S. since October. Since only a few hundred families have already been returned to their home countries and limited U.S. detention facilities can house only about 1,200 family members, the 70 percent figure suggests the government released roughly 41,000 members of immigrant families who subsequently failed to appear at federal immigration offices.

The official, who was not identified by name on the recording obtained by the AP, also said final deportation had been ordered for at least 860 people traveling in families caught at the border since May but only 14 people had reported as ordered.

The Homeland Security Department did not dispute the authenticity of the recording.

In a statement emailed Thursday afternoon, ICE spokeswoman Gillian Christensen said the no-show rate “represents an approximate snapshot of individuals encountered beginning in May” who didn’t reported to ICE. Christiansen added that some of those people may still be reporting to immigration court hearings and a “significant” number of deportation cases are still pending before judges.

The AP reported in June that the administration would not say publicly how many immigrant families from Central America caught crossing into the U.S. it had released in recent months or how many of those subsequently reported back to the government after 15 days as directed. The AP noted that senior U.S. officials directly familiar with the issue, including at the Homeland Security Department and White House, had dodged the answer on at least seven occasions over two weeks, alternately saying that they did not know the figure or didn’t have it immediately at hand.

The Homeland Security Department’s public affairs office during the same period did not answer roughly a dozen requests for the figures.

More than 66,000 immigrants traveling as families, mostly mothers and young children, have been apprehended at the border since the start of the budget year in October. Nearly 60,000 of those immigrants are from Honduras, El Salvador and Guatemala and cannot be immediately repatriated, so the government has been releasing them into the U.S. and telling them to report within 15 days to the nearest Immigration and Customs Enforcement offices.

At the meeting, the ICE official acknowledged the no-show figures while explaining the administration’s decision in June to open a temporary detention center for families in Artesia, New Mexico. A second immigration jail in Texas was later converted for families and can house about 530 people. A third such detention center will open in Texas later this year. Before the new facility in Artesia, the government had room for fewer than 100 people at its only family detention center in Pennsylvania.

Immigration advocates have complained that the new detention centers were punishing immigrants who ultimately may win lawful asylum claims to remain in the U.S. In the meeting, they also questioned whether immigration officials had clearly and properly instructed immigrants to meet with federal agents within 15 days.

The ICE official said it was necessary to detain families to ensure they didn’t vanish into the U.S. He encouraged advocacy groups to help find ways to ensure that immigrants reported to federal agents as ordered so the government could begin processing their cases, including any requests to remain in the U.S. legally.

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