The U.S. Department of Health and Human Services is considering using military bases to hold children who have been separated from their parents at the border, NBC News reports.

At this time, hundreds of children have spent more than 72 hours in custody at U.S. border stations, beyond the time limit for holding immigrants of any age in temporary facilities. Nearly half of these children are under the age of 12, according to documents obtained by the news network.

"It would be highly inappropriate and even unsafe to hold children for extended periods in these short-term border facilities because they often lack the adequate medical and nutritional resources for these young people," Greg Chen, American Immigration Lawyers Association director of government relations, told NBC.

"It would place these children at risk of harm if they are housed with adults without the proper privacy that children should have."

Border stations, which are operated by U.S. Border Patrol, most often lack sleeping space or adequate bedding for children, and are intended only as the first stop for children who have been detained at the border.

HHS is responsible for finding shelter for migrant children, as well as matching them with relatives or foster parents in the country, but it takes 45 days on average to find a sponsor for a child, according to a spokesperson for the department’s Administration for Children and Families, which cares for 11,200 unaccompanied children.

According to this spokesperson, the agency plans on touring three military bases in Texas as potential "sites for UAC (unaccompanied alien children) operations."

"What's happening now is a broad indication of a total lack of planning or forethought for the policy they enacted," Peter Boogaard, spokesman for immigration reform group FWD.us and a former Obama Administration official, told NBC. "They didn't think this through at all — what it would mean for kids, for their parents and for the operational challenges."

"Instead of having Border Patrol agents at the border, you have them taking care of kids at border stations."