Separately, 17 American states are suing the Trump administration over the border policy

A US federal judge in California has ordered that families separated at the US-Mexico border must be reunited.

More than 2,000 children have been taken away from their parents as a result of the Trump administration's 'zero tolerance' approach to illegal immigration.

Although Donald Trump has signed an order to end the practice of family separation, many children have yet to be returned to their parents.

In a preliminary injunction, Judge Dana Sabraw ruled that children under five must be reunited with their parents within 14 days, and older children within 30 days.

Officials have also been told to allow regular communication between parents and children.

The judge's ruling also temporarily halts the practice of family separation, with the judge suggesting that the executive order to end the practice "is not absolute".

The case was taken by the American Civil Liberties Union (ACLU), with the organisation's Lee Gelernt saying: “This ruling is an enormous victory for parents and children who thought they may never see each other again."

In a separate case, 17 US states are suing the Trump administration over the separation of migrant families.

California Attorney General Xavier Becerra said: "We are taking the Trump Administration to court because the safety, security and well-being of our children is too important to be threatened by a heartless political maneuver."

Yesterday the US President's travel ban - affecting mostly Muslim countries - has been backed by the country's highest court.