The Trump administration has reportedly asked the Pentagon if it can house up to 20,000 children separated from or unaccompanied by their immigrant parents on military bases.

The plan appears similar to an Obama administration policy in 2014.

Defense Secretary Jim Mattis has said the Pentagon would support the Homeland Security Department.

The Pentagon has told legislators that the Department of Health and Human Services has inquired about housing up to 20,000 children separtated from their immigrant parents on military bases as early as July, according to The Washington Post.

Lt. Col. Jamie Davis, a Pentagon spokesman, confirmed to The Post on Thursday that the Defense Department had received the request and was reviewing it.

The memo asked the Pentagon if it would be able to receive as many as 20,000 children "for occupancy as early as July through December 31, 2018."

HHS employees would be present at each site and the facilities would would be run by HHS employees or contractors, according to the memo, which said they would care for the minors, "including supervision, meals, clothing, medical services, transportation or other daily needs."

Health and Human Services officials visited Fort Bliss, Dyess Air Force Base, and Goodfellow Air Force Base in Texas last week and were scheduled to visit Little Rock Air Force Base in Arkansas.

The Pentagon told lawmakers it has to determine if it "possesses these capabilities," and, in accordance with the Economy Act, it would be reimbursed for all costs.

The plan appears to be similar to an Obama administration effort in 2014, in which about 7,000 unaccompanied minors were housed in temporary centers at Fort Sill in Oklahoma, Lackland Air Force Base in Texas, and naval Base Ventura in California.

The memo was sent to legislators on Wednesday, after Trump scrapped his administration's policy to separate children from their parents at the US's southern border.

Also on Wednesday, but prior to Trump rescinding the separation policy, Defense Secretary Jim Mattis was asked about potentially housing children at US military bases.

"We'll see what they come in with. We support [the Department of Homeland Security] and right now this is their lead and we'll respond if requested," Mattis told reporters.

"We have housed refugees. We have housed people thrown out of their homes by earthquakes and hurricanes. We do whatever is in the best interest of the country," he added, when asked if he would allow bases to house children.

When asked about the separation policy, Mattis directed questions to Homeland Security Secretary Kristjen Nielson, with whom he said the Pentagon maintained close collaboration.

"We support whatever they need," Mattis said.