Guantanamo, Cuba - Human rights groups said Wednesday they have sued to gain access to migrants held at the US military base in Guantanamo, Cuba, under President Donald Trump's offensive against undocumented foreigners.

Trump has ordered the base – synonymous with abuses against terror suspects held there after the September 11 attacks – to prepare to receive some 30,000 people who entered the US without papers.

The White House has said the first flights to Guantanamo left on February 4 and included members of the Venezuelan crime gang called the Tren de Aragua, which the Trump administration has classified as a terrorist organization.

The American Civil Liberties Union and other advocacy groups said they have filed a suit seeking access to these people on behalf of relatives of the detainees and four legal services providers.

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They said the administration has given no information on how long these people will be held at Guantanamo, in which conditions of detention, or if they will be able to contact lawyers or their families.

"By hurrying immigrants off to a remote island cut off from lawyers, family, and the rest of the world, the Trump administration is sending its clearest signal yet that the rule of law means nothing to it," said Lee Gelernt, deputy director of the ACLU's Immigrants' Rights Project.

"It will now be up to the courts to ensure that immigrants cannot be warehoused on offshore islands," Gelernt said.