President Donald Trump on Tuesday visited the new Florida detention centre dubbed "Alligator Alcatraz", where around 1,000 migrants are expected to be held as soon as next month, surveying the next step in his crackdown on illegal immigration.

While touring the facility in the Florida Everglades, Trump said it will soon house the most "menacing migrants, some of the most vicious people on the planet".

Alligators, crocodiles and pythons in the surrounding wetlands are expected to keep detainees from escaping the centre, which is being built on an old airfield.

Some state lawmakers, the local mayor and neighbours oppose its construction, saying that it could hurt an important ecosystem.

"We're surrounded by miles of treacherous swampland and the only way out is, really, deportation," Trump said on the tour.

His administration plans to build similar facilities, and the president said the new detention centre was the most impactful step that the US could take to "fully reverse the Biden migration invasion".

It will cost about $450m (£332m) a year to run and funding will mostly come from a temporary shelter and services programme that the Federal Emergency Management Agency had used for undocumented immigrants, according to Homeland Security Secretary Krisit Noem, who joined the presidential visit.

Two other Trump allies, Florida Governor Ron DeSantis and Representative Byron Donalds of Kentucky, were also on the tour.

The move to build a new centre comes as human rights organisations warn detentions centres are becoming overcrowded.

Immigration and Customs Enforcement (ICE) currently has a record 59,000 detainees in custody nationwide, 140% above its capacity, according to data obtained by CBS, the BBC's news partner.

Like the former prison Alcatraz in the middle of the San Francisco Bay, which Trump has said he wants to reopen, the facility will be hard to reach.

It will be situated on the Dade-Collier Training and Transition Airport, a public airport around 58km (36 miles) from Miami, and an area deemed an ecologically important subtropical wetland.

Florida's Attorney General James Uthmeier has described the site as a "virtually abandoned facility".

But local residents who live near the site, like Betty Osceola, a member of the Miccosukee Native American community, have told the BBC they are worried that the temporary facility will become permanent.

"I have serious concerns about the environmental damage," she said, as she stood next to a canal where an alligator was swimming.

Experts warn the damage to area wetlands and endangered species could undo the state's massive effort to restore the Everglades, which has cost Florida billions of dollars. It is home to endangered species such as the Florida panther and the West Indian manatee.

Elise Pautler Bennett, an attorney at the Center for Biological Diversity, described the Everglades as "the most sensitive place in Florida", making development of a detention centre there "risky".

"Any other project that would have been proposed in the Everglades would have gone through an intense environmental approval process, I'm convinced this one didn't get that because it's a political stunt," Ms Bennett told the BBC.

It has been estimated that the detention centre could be up and running in 30 to 60 days and could hold an estimated 1,000 people.

"This is an efficient and low-cost way to help carry out the largest mass deportation campaign in American history," White House Press Secretary Karoline Leavitt said ahead of Trump's visit. (BBC)