US Defence Secretary James Mattis has said that two military bases in Texas will be used to house detained migrants, whose numbers have swelled under a recent “zero tolerance” policy.

Fort Bliss, an Army base in El Paso, and Goodfellow Air Force Base in San Angelo will house the detained migrants, including families and unaccompanied minors. But Mattis on Monday said he could not confirm details, such as the number of migrants to be sheltered at the bases or the type and size of the shelters.

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

“We’ll provide whatever support the Department of Homeland Security needs in order to house the people that they have under their custody,” Mattis said. “We will work that out week by week. The numbers obviously are dynamic so we will have to stay flexible in our logistics support.”

According to an earlier report, the US 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, Dallas News reported.

The US 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 caused the number of immigrants in US government custody to swell, exceeding previous rooming capacity and prompting the US government to turn to the military for extra space.

The Trump administration also faced backlash over the policy leading to the separation of thousands of immigrant children from their parents at the US-Mexico border.

Trump later reversed his own policy amid international fury and signed an executive order intended to end family separations.