Four families separated at the southern border under former President Donald Trump will be reunited in the United States this week, the Biden administration revealed this week.

Speaking to reporters Sunday, Homeland Security Secretary Alejandro Mayorkas declined to offer the identities of the children, only describing them as from age 3 to “teenagers who have had to live without their parent during their most formative years” at the time of separation.

All of the children are already in the US. Immigration officials will provide the parents with humanitarian parole to enter the country to reunify.

The reunions are expected to occur sometime between Monday and Wednesday.

“We continue to work tirelessly to reunite many more children with their parents in the weeks and months ahead. We have a lot of work still to do, but I am proud of the progress we have made and the reunifications that we have helped to achieve this week,” the DHS secretary told reporters.

While the Biden administration may take credit for reunifying these families, one top official at an immigrant advocacy group pushed back on the idea that such praise was deserved.

“Despite what Secretary Mayorkas would have the public believe, DHS has done nothing to facilitate the return and reunification of these parents this week, other than to agree to allow them in,” Carol Anne Donohoe, managing attorney of Al Otro Lado’s Family Reunification Project, told NBC News Monday.

“The only reason these mothers will be standing at the port of entry is because Al Otro Lado negotiated their travel visas with the Mexican government, paid for their airline tickets and arranged for reunification.”

As part of its “zero-tolerance” immigration policy, the Trump administration began separating children and parents caught crossing the US border illegally in 2017 in an effort to deter migration.

Immigrant rights groups and the public alike began expressing their dismay at the policy after it became publicized in 2018, with backlash growing so intense that the then-president signed an executive order ending the policy.

Now, under a new president, a different crisis has emerged at the border.

The Biden administration’s undoing of Trump’s border policies has prompted a flood of Central American and Mexican illegal migrants at the US border, including thousands of unescorted children.

Central Americans looking for refuge from the Northern Triangle countries — Guatemala, Honduras and El Salvador — have taken these policy moves, as well as the overwhelmingly more welcoming tone from Democrats, as a sign that President Biden is inviting them to cross the border.

Insisting that the border was not facing a crisis, Mayorkas said in early March that the problems the agency faced should be blamed on the previous administration.

The data, however, overwhelmingly shows that migrants were flooding the border because they believed Biden would welcome them with open arms.

As Mayorkas denied the existence of a crisis, Mexican President Andrés Manuel López Obrador blamed the new president for the crisis, arguing that the “expectations” he set left migrants with the perception that they would be let into the US.

With Post wires