A US appeals court has ruled that a Florida migrant detention centre known as "Alligator Alcatraz" can remain open for now.

A lower court judge had barred the Trump administration and Florida officials last month from bringing any new migrants to the facility and for much of the site to be dismantled, effectively shutting it down.

But a three-judge panel of the 11th Circuit Court of Appeals ruled on Thursday that the detention centre can remain open while a Trump administration appeal of the shutdown order is being heard.

The majority ruled that the project — which has been funded by the state of Florida — did not trigger the kind of environmental review needed for federally funded construction projects.

Friends of the Everglades and the Center for Biological Diversity filed a lawsuit arguing that the facility threatens the sensitive Everglades wetlands ecosystem and was hastily built without the legally required environmental impact studies.

The centre was assembled in just eight days in June with bunk beds, wire cages and large white tents at an abandoned airfield in the Everglades, home to a large population of alligators.

'Open for business'

Florida Governor Ron DeSantis said in a video posted to social media on Thursday that the detention facility was "open for business" and ready to support President Donald Trump's immigration enforcement efforts.

The US Department of Homeland Security called the ruling a "huge victory" in a social media post.

"This lawsuit was never about the environmental impacts of turning a developed airport into a detention facility," DHS said. "It has and will always be about open-borders activists and judges trying to keep law enforcement from removing dangerous criminal aliens from our communities, full stop."

Trump, who has vowed to deport millions of undocumented migrants, visited the detention site after its opening, boasting about the harsh conditions and joking that the reptilian predators will serve as guards.

The White House has nicknamed the facility "Alligator Alcatraz," a reference to the former island prison in San Francisco Bay that Trump has said he wants to reopen.

The centre was planned to hold 3,000 undocumented migrants, according to Homeland Security Secretary Kristi Noem.

A district judge last month ordered a halt to further construction at the detention centre and for it to be dismantled in 60 days.