Democratic attorneys general in 17 U.S. states filed a lawsuit against the Trump administration Tuesday for separating migrant parents from their children at the U.S.-Mexico border in an effort to force the White House to reunite them.

The attorneys generals of the states, including New York, Illinois and California, joined Washington, D.C. in filing the lawsuit in U.S. District Court in Seattle in the first legal challenge by states over the controversial policy.

"The administration's practice of separating families is cruel, plain and simple," New Jersey Attorney General Gurbir Grewal said in a statement.

"Every day, it seems like the administration is issuing new, contradictory policies and relying on new, contradictory justifications. But we can't forget: the lives of real people hang in the balance."

The states suing are Massachusetts, California, Delaware, Iowa, Illinois, Maryland, Minnesota, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia and Washington.

Referring all undocumented adults for criminal prosecution is a key part of Trump's “zero tolerance” policy and has resulted in over 2,300 children being separated from their parents during criminal proceedings after Trump changed decades of past administration practice.

Prior administrations did not immediately refer all undocumented adults for criminal prosecution regardless of whether they illegally crossed the border with children.

Many parents are now in custody thousands of miles from their children, whom they have not been able to see and have rarely spoken to for at least a month.

Following a countrywide uproar, the Trump administration has put a temporary pause on referring undocumented parents traveling with their children for criminal prosecution but did not terminate its zero tolerance policy and did not specifically outline whether children would be returned to their parents.

The immigration crackdown comes as Guatemala seeks protected status for its citizens following a devastating volcano eruption in the country near the capital. (Anadolu)