WASHINGTON: US President Donald Trump signed a bill on Wednesday ordering the pre-trial detention of undocumented migrants charged with theft and violent crime — his first piece of legislation since he returned to power.

Signing the Laken Riley Act, named for a 22-year-old US student murdered by a Venezuelan migrant, Trump said: “With today´s action, her name will… live forever in the laws of our country, and this is a very important law.”

Trump said on Wednesday he planned to detain “criminal illegal aliens” at the notorious Guantanamo Bay military prison, used for holding terrorism suspects since the 9/11 attacks.

Trump said at the White House that he was “signing an executive order to instruct the Departments of Defence and Homeland Security to begin preparing the 30,000 person migrant facility at Guantanamo Bay.”

The Guantanamo prison was opened in the wake of the 9/11 attacks and has been used to indefinitely hold detainees, many of whom were never charged with a crime, seized during the wars and other operations that followed.

At its peak about 800 people were incarcerated at the site on the eastern tip of Cuba. Testimony from detainees documenting their abuse and torture by US security personnel have long prompted domestic and international criticism.

The conditions there and the denial of basic legal principles have sparked consistent outcry from rights groups, and UN experts have condemned it as a site of “unparallelled notoriety.”

Former Democratic presidents Joe Biden and Barack Obama both pledged to close the facility, but both left office with the prison still open.

Last September, the New York Times obtained government documents showing that the Guantanamo Bay military base has also been used for decades by the United States to detain migrants intercepted at sea, but in an area separate from that used to hold those accused of terrorism.

Trump signed an executive order on Wednesday to combat antisemitism and pledge to deport non-citizen college students and others who took part in protests, a White House official said.

A fact sheet on the order promises “immediate action” by the Justice Department to prosecute “terroristic threats, arson, vandalism and violence against American Jews” and marshal all federal resources to combat what it called “the explosion of antisemitism on our campuses and streets”.