EL PASO, Texas -- The surge of migrants arriving at the southern border has led the Trump administration to dramatically expand a practice it has long mocked as "catch and release."

With processing and holding centres overwhelmed, the administration is busing migrants hundreds of miles inland and releasing them at Greyhound stations and churches in cities like Albuquerque, San Antonio and Phoenix because relief organizations in towns close to the border cannot keep up with the flow.

Since Dec. 21, U.S. Immigration and Customs Enforcement has set free about 108,500 people who came as families. On some days, more than 1,000 people were released in Texas' Rio Grande Valley alone.

San Antonio received part of that surge in recent days, forcing the city to open a help centre for migrants arriving at the downtown bus station.