The Trump administration will reallocate $271 million in funding from the Department of Homeland Security to pay for detention space and hearing locations for asylum-seekers sent to wait in Mexico under a controversial Trump administration policy.

The money includes $155 million that will be pulled from the Federal Emergency Management Agency's Disaster Relief Fund and given to Immigration and Customs Enforcement to fund locations for asylum hearings at the border, according to a letter from Democratic Rep. Lucille Roybal-Allard of California that was obtained by NBC News.

In addition, $116 million originally budgeted for Coast Guard operations, aviation security and other initiatives will pay for some 6,800 additional beds for immigrant detainees, according to NBC.

The government notified Congress of the reallocation in a memo at the end of July, according to reports.

Beds for detained immigrants were a sticking point earlier this year during appropriations negotiations in Congress, with Democrats seeking to limit the number of beds immigration agencies have to detain immigrants while their cases are working through the court system.

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A final spending package included funding for about 45,000 beds a day, an increase over last year but still about 7,000 beds short of the administration's request. In recent months, ICE has been holding far more immigrants in detention than is budgeted. As of Aug. 10, more than 55,000 people were being detained by ICE. The additional funding will bring the number of beds budgeted for to about 50,000.

The Trump administration earlier this year began to send some migrants back to Mexico to await their court hearings in the U.S., despite a lack of housing and aid. The asylum courts the government intends to set up on the border will be used to adjudicate the cases of the migrants in Mexico.

DHS says the reallocation of funds is necessary because of the influx of migrants at the border this year and the fact that it predicts ICE will run out of money for detaining migrants before the end of the fiscal year in September. Authorities this year have apprehended or deemed inadmissible migrants at levels not seen in over a decade.

Advocates and policy experts, however, say the government is detaining migrants it could release – such as asylum-seekers and migrants with no criminal records – resulting in the high number of detainees in government custody.

The move has already drawn fire from Democrats, who argue the agency is overriding Congress to fund more detention beds and immigration operations and who are concerned about the diverted funds.