US President Donald Trump has ordered the construction of a migrant detention facility in Guantanamo Bay which he said would hold as many as 30,000 people.

He said the facility at the US Navy base in Cuba, which would be separate from its high-security military prison, would house "the worst criminal illegal aliens threatening the American people".

Guantanamo Bay has long been used to house immigrants, a practice that has been criticised by some human rights groups.

Later on Wednesday, Trump's "border tsar" Tom Homan said the existing facility there would be expanded and run by Immigration and Customs Enforcement (ICE).

He said the migrants could be transported there directly after being intercepted at sea by the US Coast Guard, and that the "highest" detention standards would be applied.

It is unclear how much the facility will cost or when it would be completed.

Cuba's government swiftly condemned the plan, accusing the US of torture and illegal detention on "occupied" land.

Trump's announcement came as he signed the so-called Laken Riley Act into law, which requires undocumented immigrants who are arrested for theft or violent crimes to be held in jail pending trial.

The bill, named after a Georgia nursing student who was murdered last year by a Venezuelan migrant, was approved by Congress last week, an early legislative win for the administration.

At a signing ceremony in the East Room of the White House, Trump said the new Guantanamo executive order would instruct the departments of defence and homeland security to "begin preparing" the 30,000-bed facility.

"Some of them are so bad we don't even trust the countries to hold them, because we don't want them coming back," he said of migrants. "So we're going to send them to Guantanamo... it's a tough place to get out."

According to Trump, the facility will double the US capacity to hold undocumented migrants.

The US has already been using a facility in Guantanamo - known as the Guantanamo Migrant Operations Center (GMOC) - for decades and through various administrations, both Republican and Democrat.

In a 2024 report, the International Refugee Assistance Project (IRAP) accused the government of secretly holding migrants there in "inhumane" conditions indefinitely after detaining them at sea.

The GMOC has principally housed migrants picked up at sea and was recently the subject of a Freedom of Information request by the American Civil Liberties Union for the disclosure of records about the site.

The Biden Administration responded that it "is not a detention facility and none of the migrants there are detained".

The Trump administration, however, says the planned expanded facility is very much intended as a detention centre.

It will reportedly ask Congress to fund the expansion of the existing detention facility as part of a spending bill Republicans are working to assemble.

When asked by reporters at the White House, Homeland Security Secretary Kristi Noem said only that the money would be allotted through "reconciliation and appropriations".

The military prison on Guantanamo has, for decades, held detainees taken into US custody after the 9/11 attacks on the US in 2001.

At its peak it held hundreds of prisoners, and several Democratic presidents including Barack Obama have vowed to close it. There are 15 prisoners currently being held there.

News of the facility's expansion was met with swift condemnation by the Cuban government, which has long considered Guantanamo Bay to be "occupied" and has denounced the existence of a US naval base on the island ever since Fidel Castro swept to power in 1959.

"In act act of brutality, the new government of the US has announced it will incarcerate, at the naval base at Guantanamo, located in illegally occupied Cuban territory, thousands of forcibly expulsed migrants, who will be located near known prisons of torture and illegal detention," Cuban President Miguel Díaz-Canel wrote on X.

The Cuban Foreign Minister, Bruno Rodriguez, said the announcement showed "contempt for the human condition and international law".