Migrants separated from their children after they were detained for illegally entering the United States have filed a class action lawsuit, claiming there are "hundreds" of parents in the same situation, and that the Trump administration is violating their due process rights.

Class action

The lawsuit, brought by the American Civil Liberties Union and filed in US District Court in southern California, on Friday, expands on the claim of a single Congolese asylum seeker filed last week. Ms L, as she is referred to in the complaint, had been detained in San Diego while her seven-year-old daughter was sent to Chicago four months ago by federal authorities. But on Tuesday, just days after the initial lawsuit was filed, Ms L was released.

The class action seeks to represent all adult parents in immigration custody who have a minor child separated from them without a hearing to prove the parent is unfit to care for them.

In the class action complaint, Ms L is joined by another anonymous lead plaintiff. Ms C is a woman from Brazil who crossed the border and told officials she hoped to apply for asylum in the US. She was prosecuted on a misdemeanour charge of entering the country illegally and served a 25-day sentence in jail, while her 14-year-old son was sent to a facility in Chicago, the lawsuit says. On September 22, she was transferred to immigration detention in Texas and has still not been able to reunite with her son.

BREAKING: We filed a national class-action lawsuit against the Trump administration for forcibly separating parents and young children — ACLU (@ACLU) March 9, 2018

Separating families

The administration has floated the idea of separating families at the border in an attempt to deter migration.

The Department of Justice declined to comment on pending litigation.

The Department of Homeland Security (DHS) said that it does not currently have a policy of separating families but that it does so at times if a child may be at risk.

"There have been numerous intelligence reports and cases where kids have been used and trafficked by unrelated adults in an effort to avoid detention," Tyler Houlton, a DHS spokesman, said in a statement. "If we are unable to confirm this relationship, we must take steps to protect the child."

But Democratic legislators have spoken out against that idea and the American Academy of Pediatrics said in a statement that family separation measures "are harsh and counterproductive".