A federal judge in San Diego issued an order on Monday barring officials from deporting newly reunited immigrant families for up to one week.

District Judge Dana Sabraw was responding to papers filed by the American Civil Liberties Union (ACLU) expressing concern that the government planned to carry out quick deportations.

Attorneys said newly reunited families should be given time to talk through whether they plan to seek asylum and mull over the possible ramifications for both the parents and the children.

"The judge once again made clear that the government unconstitutionally took these children away and now must do everything in its power to reunite them safely and by the deadline," Lee Gelernt, of the ACLU's Immigrants' Rights Project, said in a statement.

Sabraw earlier gave officials a July 26 deadline to return children over age five who were separated from their families at the border with Mexico.

The estimated number of children separated at the border under the Trump administration's "zero-tolerance" policy has fluctuated, but as many as 3,000 children are believed to have been affected.

Senior administration figures, from Homeland Security Secretary Kirstjen Nielsen and Attorney General Jeff Sessions to the president himself, have been heavily criticized for lying or giving otherwise misleading statements on child separation.

These have included blaming the policy on the Democrats, wrongly implying that illegal immigrants are more violent than the US population, giving a false perception of the size of the problem and misappropriating Christian dogma to justify the policy.

The administration has also falsely stated on various occasions that laws or court rulings were forcing them to separate families when in fact the policy was introduced by choice.

The federal government missed a July 10 deadline imposed by Sabraw for the reunification of children under age five with their families.

But officials said late Thursday they had reunited 57 of 103 children, insisting the others were ineligible for reunification for reasons ranging from safety concerns and parents who had already been deported or were in custody for other offenses.

Government officials had earlier asked for more time to complete the reunifications, claiming they needed more time to ensure the children's safety and confirm their parental relationships.

A federal judge has temporarily blocked the Trump administration from deporting parents and children that it forcibly separated.