A US federal judge on Thursday temporarily halted new construction at an immigration detention facility in Florida dubbed "Alligator Alcatraz" while a lawsuit over its environmental impact plays out.

At a hearing in Miami, US District Judge Kathleen Williams blocked new construction at the site in the Florida Everglades through August 12 but did not suspend operations or otherwise interfere with the work of immigration officials there.

The ruling is a setback for US President Donald Trump as he seeks to ramp up deportations of migrants and others living in the US illegally.

US Department of Homeland Security spokesperson Tricia McLaughlin said the lawsuit ignores the fact that the land at issue has already been developed for a decade.

"It is another attempt to prevent the President from fulfilling the American people's mandate for mass deportations," McLaughlin said in a statement.

Trump has made Alligator Alcatraz emblematic of his hardline immigration policies, boasting of its location in a vast tropical wetland teeming with alligators, crocodiles and pythons.

Officials have estimated the facility could cost US$450 million annually and house some 5,000 people.

In their lawsuit seeking to block construction at the site, environmental and tribal groups say it threatens sensitive wetland ecosystems, endangered species and essential waterways.

"It's a relief that the court stepped in to protect the Everglades' sensitive waters, starry skies and vulnerable creatures from further harm while we continue our case,” said Elise Bennett, an attorney representing the Centre for Biological Diversity in the lawsuit, in a statement on Thursday.

Other critics of Alligator Alcatraz have condemned the facility as inhumane and dangerous to detainees.

The American Civil Liberties Union is separately seeking to block deportations from the facility, saying detainees are being held without charges and denied their constitutional rights to speak to their lawyers. (Reuters)