The administration of the United States President, Donald Trump again doubled down on its policy of separating families at the border as audio of crying children in a so-called "immigration shelter" generated further outrage over the approach. 

"Papa! Papa!" one child weeps as screams and cries of others are heard in an audio clip released by ProPublica, a US-based media outlet, on Monday.

"Well, we have an orchestra here, right?" a Border Patrol agent is heard saying in the clip. "What's missing is a conductor."

According to ProPublica, the clip was obtained from prominent civil rights lawyer Jennifer Harbury who was given the audio by an unidentified individual who recorded the children in a detention centre.

The now-viral clip has driven anger that continues to mount against US President Donald Trump, whose administration has introduced a "zero-tolerance" approach towards migrants and refugees who cross the US southern border without documents. 

Part of the policy has been separating children from their parents who are detained.