The Trump administration has announced new rules which would allow authorities to indefinitely detain migrant families who cross the border illegally.
The US Department of Homeland Security is moving to replace a decades-old court agreement known as the Flores Settlement Agreement (FSA).
Introduced in 1993, the agreement strictly regulates the detention and treatment of minors in immigration facilities - including limits on how long they can be detained in custody.
However, in a move likely to be challenged in court, changes have now been announced which the US government says would "terminate" the FSA.
According to the New York Times, the proposed changes - which must be approved by a federal judge before coming into force - would abolish a 20-day limit on detaining families in immigration jails.
Instead, officials would be able to hold families with children in "licensed facilities or facilities that meet ICE’s [Immigration and Customs Enforcement] family residential standards" until their cases are decided.
The administration claims new rules are necessary given the "statutory and operational changes" since the original agreement, such as increased numbers of unaccompanied children crossing the southern border.
Acting Secretary of Homeland Security Kevin McAleenan argued: "Today, the government has issued a critical rule that will permit the Department of Homeland Security to appropriately hold families together and improve the integrity of the immigration system.
"This rule allows the federal government to enforce immigration laws as passed by Congress and ensures that all children in US government custody are treated with dignity, respect, and special concern for their particular vulnerability."
The new rules are set to take effect in 60 days.
Responding to the announcement, civil rights group ACLU said the planned measures represented a "cruel attack on children" and called on Congress to not fund the efforts.
