The girl – who illegally crossed the border from Mexico along with her father and dozens of others – died of “dehydration and shock,” the newspaper reported, citing the US Customs and Border Protection.

The child – whom CBP said “reportedly had not eaten or consumed water for several days” – began having seizures over eight hours after being detained, was flown to a hospital and died there, the Post said.

Donald Trump has made hard-line immigration policies a central plank of his presidency, drawing fire from critics who accuse him of demoniSing migrants for political gain.

He vowed to build a wall on the border with Mexico, deployed thousands of US troops there and separated more than 2,000 migrant children from their parents as part of a “zero tolerance” policy on illegal immigration.