Donald Trump is facing growing condemnation for his policy of separating migrant families - but he's holding firm.

The US president is defending the separation of nearly 2000 children from their parents at the US-Mexico border in the past two months.

Opponents are focusing on the fate of children at the rapidly growing detention centre for children in El Paso, Texas.

Even fellow Republicans, like former first lady Laura Bush, are labelling the policy shameful and immoral.

Correspondent Ashley Claster told Kate Hawkesby no can seems to know exactly why the children are being detained.

"They don't know if these kids came to the border unaccompanied already, or if they came to the border and then got separated from their families."