The cost of holding migrant children who have been separated from their parents in “tent cities” is $775 per person per night — far more expensive than keeping kids with their parents in detention centers, a new report said Wednesday.

The reason for the higher cost to taxpayers, according to an official at the Department of Health and Human Services, is that the need to arrange for security, bring in air conditioning, medical workers and other government contractors is much higher than the costs for existing facilities that are already staffed, NBC News reported.

It costs $256 per night to hold kids in permanent HHS facilities like Casa Padre in Brownsville, Texas.

Keeping them with their parents in detention centers like the one run by ICE in Dilley, Texas, cost $298 per person per night, according to an agency estimate when it awarded the contract for the facility in 2014, the network reported.

The cost to operate a 400-bed temporary structure for a month at capacity would top $5 million, and the average stay for separated kids is nearly two months.

The HHS official said the agency is “aggressively looking for potential sites” for more tent cities to accommodate the surge of migrant children taken from their parents by the Trump administration’s “zero tolerance” policy.