The acting commissioner of the US Customs and Border Protection (CBP) agency, John Sanders, is resigning and will leave his post on July 5, amid an outcry over the treatment of detained migrant children.

His departure comes amid mounting public backlash over alarmingly unsanitary conditions at an overcrowded migrant facility in Clint, Texas where the discovery of poor care and lack of access to showers or clean clothing prompted the relocation of 250 detained children.

The situation has led immigration activists and Democrats to step up criticism of President Donald Trump's hard-line immigration policies.

Mr Sanders, whose resignation was first reported by The New York Times, has led the agency since April, when Mr Trump reshuffled the management of US immigration agencies under the Department of Homeland Security.

Before taking over CBP, he was the agency's chief operating officer and had also been the Transportation Security Administration's chief technology officer.