Washington DC - More than 200 organizations signed a letter this week urging Congress members to reject plans to significantly expand the US' immigrant detention system.

"We, the undersigned 205 organizations, write to express our extreme alarm over the Trump administration's dangerous and unprecedented plans to drastically expand the abusive immigration detention system by proliferating into military bases, and negotiating new or expanded contracts with private prison companies and law enforcement agencies across the United States and beyond," reads the letter signed by United We Dream, the National Immigration Law Center, the Immigrant Defense Project, Haitian Bridge Alliance, and more.

The warning comes amid reports the Trump administration plans to open new detention facilities and recommence family detentions, as well as prepare a 30,000-bed detention facility at the US' notorious Guantánamo Bay Naval Base in Cuba.

Donald Trump has already taken a series of executive actions designed to accelerate and expand his mass deportation agenda, including halting refugee admissions to the US, revoking birthright citizenship, and extending fast-track removal proceedings. Some of the orders have been paused amid legal challenges.

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The Department of Homeland Security, meanwhile, has rescinded restrictions on immigration raids at schools, hospitals, houses of worship, and other areas deemed "sensitive." It has also sought to end Temporary Protected Status for Venezuela and Haiti, potentially leaving hundreds of thousands more people vulnerable to deportation.

"There are already nearly 40,000 people locked up in [US Immigration and Customs Enforcement] ICE detention – if Trump’s multi-pronged detention expansion plan is realized, it will at least triple the immigration detention system’s capacity," the letter states.

"We urge Members of Congress to vocally oppose Trump’s cruelty and boldly deny Trump the resources he needs to carry out unconstitutional and un-American plans, including by cutting funding to ICE, Customs and Border Protection (CBP), and any other agencies that would be used to carry out mass detention and deportations."