Hundreds of migrant children still not returned to parents amid warnings they are disappearing into ‘black hole’

More than 700 migrant children remain in custody after being separated from their families despite a court order that they be reunited with relatives by Thursday evening.

In a court filing, the Trump administration said more than 1800 migrant children had been handed back to family members in time for a deadline set by a federal judge in San Diego.

That still leaves more than 700 children who were not "eligible" to be reunited, including 431 with parents who have already been deported.

The American Civil Liberties Union, which brought the case against the government, said the data showed "dozens of separated children still have not been matched to a parent".

And immigration campaigners said the government’s attempts to meet the deadline were characterised by confusion and risked leaving children in a "black hole".

Maria Odom, vice president of legal services for Kids in Need of Defence, said two children who were represented by the group were sent from New York to Texas to be reunited with their mother. When they arrived, they learned their mother had already been deported, she said.

Her group now cannot find the children, aged 9 and 14.

It was an example, she added, "of how impossible it is to track these children once they are placed in the black hole of reunification."

The story behind photograph that revealed a scandal

The Trump administration’s "zero tolerance" policy toward illegal immigration led to the separation of about 2,500 children while their parents, some asylum seekers, went through a legal process.

An outcry at home and abroad forced President Donald Trump to order a halt to the separations in June. US Judge Dana Sabraw in San Diego ordered the government to reunite the families and set Thursday as the deadline.

Mr Sabraw has criticised some aspects of the process, but in recent days, he has praised government efforts. As of Monday, 900 people had received final orders of removal, and civil rights groups said they must decide if they want to return home as a family or leave their child in the United States to fight for asylum separately.

Government lawyers told a federal judge this week that 917 parents may not be eligible for prompt reunification because they have already been deported, have waived reunification, have criminal backgrounds, or are otherwise deemed unfit. The group included 463 the government said are no longer in the United States.

Rights activists said some may have been coerced or misled into returning home, believing it was the only way to see their child. Government officials have said everyone in an immigration detention center has been given notice of their rights and contact information for a lawyer.

One immigrant, Douglas Almendarez, told Reuters he believed that returning to Honduras was the only way to be reunited with his 11-year-old son.

"They told me: ‘He’s ahead of you’," said Mr Almendarez, 37, in the overgrown backyard of his modest soda shop several hours drive from the Honduran capital of Tegucigalpa. "It was a lie."

As he has previously stated during his time in office, Jeff Sessions, attorney general, on Thursday said voters backed Mr Trump, who made his hardline immigration stance a keystone of his 2016 election campaign.

"We have a very generous legal immigration system," he said in Boston. "But the illegality must end. That’s what the American people want."