People take part in a protest against U.S. immigration policies outside the U.S. embassy in Mexico City on June 21, 2018. (Xinhua/AFP)

WASHINGTON, June 25 (Xinhua) -- U.S. Secretary of Defense James Mattis said Monday that two military bases in the state of Texas will be used to house detained migrants, whose numbers have swelled under a recent "zero tolerance" policy.

"That is confirmed now that that would be the two bases -- Goodfellow Air Force Base and Fort Bliss," Mattis said at a press conference. "But I cannot confirm the specifics on how they'll be used."

Mattis stopped short of saying how many migrants will be placed at those bases.

The announcement came after the U.S. Department of Homeland Security and the Department of Health and Human Services had requested aid in providing lodging for migrants who await trial.

A report previously disclosed by the press suggests that the U.S. Navy is planning to construct temporary shelters for migrants near military bases in the states of Alabama, California and others.

The proposed project in Alabama would house approximately 25,000 people for up to one year.

The U.S. Department of Justice in April told border agents to detain all immigrants who enter the country illegally until a trial determines their fate.

The policy has caused the number of immigrants in U.S. government custody to balloon, exceeding previous rooming capacity and prompting the U.S. government to turn to the military for extra space.