The Department of Defense has been "asked to support HHS with the request for 20,000 beds," the official said, on condition of anonymity.

The request came one day after President Donald Trump moved to end the practice of splitting migrant families, with over 2,300 children recently separated from their parents under a "zero tolerance" policy.

But the US government has also been examining whether it can use military bases to house the far greater number of unaccompanied children who routinely cross the US border from Mexico.

In an executive order Trump Wednesday instructed the Department of Defense to make available existing facilities to house migrant families, or to build new ones if necessary.

HHS had been considering for weeks the possibility of using military bases in the southern United States -- three in Texas and one in Arkansas -- to house minors who cross the border unaccompanied.