The Trump administration said is preparing to circumvent limits on the government's ability to hold minors in immigration jails by withdrawing from the Flores Settlement Agreement, the federal consent decree that has shaped detention standards for underage migrants since 1997.

The manoeuvre is almost certain to land the administration back in court, where US District Court Judge Dolly Gee, who oversees the agreement, has rejected attempts to extend the amount of time migrant children can be held with their parents beyond the current limit of 20 days.

But under changes proposed on Thursday by the Department of Homeland Security and the Department of Health and Human Services, the administration said it would issue new regulations that "satisfy the basic purpose" of the Flores settlement and ensure migrant children "are treated with dignity, respect and special concern for their particular vulnerability as minors."

"Today, legal loopholes significantly hinder the Department's ability to appropriately detain and promptly remove family units that have no legal basis to remain in the country," said DHS Secretary Kirstjen Nielsen, in a statement. "This rule addresses one of the primary pull factors for illegal immigration and allows the federal government to enforce immigration laws as passed by Congress."

The proposal sets up a new immigration battle in court and comes less than three months after the Trump administration's short-lived attempt to halt an increase in illegal migration by separating children from parents who entered unlawfully. The practice was widely condemned and forced the administration to reverse course and regroup.

Thursday's proposed changes amount to the administration's new attempt to eliminate what it views as major obstacles to effective immigration enforcement. Homeland Security officials say the limits on detaining families have effectively sent a message to would-be migrants that any parent who brings a child can expect to be quickly released from custody after entering the country illegally.

The changes proposed by the administration would allow US Immigration and Customs Enforcement (ICE) to expand its family detention facilities in order to keep parents and children together in custody for lengthier periods. ICE currently has three such facilities, which it calls "family residential centres," with a combined capacity of about 3,500 beds.

But those facilities are almost always full, and the limitations on child detention under the Flores settlement have been a disincentive to build more. The settlement also mandates that children can only be held in licensed facilities and the government has struggled to find states willing to do so.

While states typically license child-care facilities, none currently issues licenses to family detention centres.

According to the changes proposed on Thursday, the government will ensure new detention facilities meet current standards, "as evaluated by a third-party entity engaged by ICE." The announcement does not indicate who the third party would be.

Homeland Security officials say that will ensure that those families, many of whom are Central Americans seeking asylum, appear in immigration court.

Undocumented immigration across the US-Mexico border Show all 14 1 /14 Undocumented immigration across the US-Mexico border Undocumented immigration across the US-Mexico border Immigrant children, many of whom are separated form their parents, are housed in Texas' tent city Reuters Undocumented immigration across the US-Mexico border A two-year-old Honduran asylum seeker cries as her mother is searched and detained near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Undocumented migrants ride on the top of a freight train referred to as the beast, or La Bestia Getty Undocumented immigration across the US-Mexico border A cage inside a US Customs and Border Protection detention facility in Texas Reuters Undocumented immigration across the US-Mexico border US Border Patrol Academy All new agents must complete a months-long training course at the New Mexico facility before assuming their posts at Border Patrol stations, mostly along the US-Mexico border Getty Undocumented immigration across the US-Mexico border US-Mexico border fence A group of young men walk along the Mexican side of the US-Mexico border fence in a remote area of the Sonoran Desert Getty Undocumented immigration across the US-Mexico border US-Mexico border fence in the US Man looks through US-Mexico border fence into the US in Tijuana, Mexico Getty Undocumented immigration across the US-Mexico border US-Mexico border fence US Border Patrol agent Sal De Leon stands near a section of the US-Mexico border fence while stopping on patrol on in La Joya, Texas Getty Undocumented immigration across the US-Mexico border US Border Patrol Academy US Border Patrol instructor yells at trainees after their initial arrival to the academy Getty Undocumented immigration across the US-Mexico border Memorial service in Guatemala Families attend a memorial service for two boys who were kidnapped and killed in San Juan Sacatepequez, Guatemala. Crime drives emigration from Guatemala to the United States, as families seek refuge from the danger Getty Undocumented immigration across the US-Mexico border Arrests on the border Undocumented immigrants comfort each other after being caught by Border Patrol agents near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Detention holding facility A boy from Honduras watches a movie at a detention facility run by the US Border Patrol Getty Undocumented immigration across the US-Mexico border Mexican farm workers Mexican migrant workers harvest organic parsley at Grant Family Farms in Wellington, Colorado Getty Undocumented immigration across the US-Mexico border Mexican family in Arizona A Mexican immigrant family sits in the living room of their rented home in Tuscon, Arizona. The family that Arizona's new tough immigrant law had created a climate of fear in the immigrant community. Getty

The Trump administration said Thursday's proposed changes would also "formalise" the way Health and Human Services cares for migrant children in its custody. The agency oversees a network of about 100 shelters for underage migrants who arrive without a parent or who have been separated. But in recent months allegations of mistreatment and sexual abuse at several shelters have emerged and HHS has been sharply criticised for not keeping better track of children after they are released to family members or other approved "sponsors."

The administration's plans to lift limits on child detention is likely to trigger new legal challenges and could revive still-simmering anger over the Trump administration's separation of 2,600 migrant children from their parents under a border crackdown this spring. As of last week, more than 500 children were still in federal custody without their parents.

The 1997 Flores Settlement Agreement resulted from a class-action lawsuit over the treatment of migrant children in federal custody.

The proposed regulations would not take effect immediately. Publishing them in the Federal Register triggers a 60-day period for public comments. Then, advocates say, the Flores counsel who represents all migrant children in federal custody would have 45 days to challenge those regulations in court.

The proposal comes weeks after the Trump administration failed to obtain permission to detain children for unspecified periods of time from Judge Gee in Los Angeles.

Justice Department lawyers had asked for permission to detain children and parents together until their cases are adjudicated, a process that can take months.

In July, Ms Gee sharply rebuked the Justice Department's request, calling it "a cynical attempt, on an ex parte basis, to shift responsibility to the judiciary for over 20 years of congressional inaction and ill-considered executive action that have led to the current stalemate."

Advocates say the Trump administration has the authority to create regulations to replace the court agreement, but they worry that officials will ignore the substantive protections in its quest to deport immigrants.

In August, the mother of a Guatemalan toddler filed a claim alleging the little girl died in May as a result of negligent medical care while detained with hundreds of other families in Texas.

"The Trump administration is seeking to expand its power to jail families for longer in worse conditions and lock up children indefinitely in unlicensed and inhumane facilities," said Ai-jen Poo, director of the National Domestic Workers Alliance, in a news conference last month.

"We're talking about an administration that intentionally and forcibly separated children from their parents knowing the torment and trauma that that would cause and we're now allowing them to set a new standard ... of care for immigrant children."