WASHINGTON >> Civil rights attorneys sued the Trump administration on Wednesday to gain access to detained migrants who they say have been flown to Guantanamo Bay and held there without being able to consult lawyers or speak to relatives.

The federal lawsuit, filed in Washington, D.C., and backed by the American Civil Liberties Union, says this is the first time in U.S. history that the government has detained non-citizens on civil immigration charges at the U.S. naval base in Cuba.

“And it is holding them incommunicado, without access to attorneys, family, or the outside world,” the lawsuit says.

The Department of Homeland Security, which is among the agencies sued, says there is a way for detainees to reach lawyers by telephone.

For decades, the naval base was primarily used to detain foreigners associated with the Sept. 11, 2001, attacks. More than 50 detained migrants were transferred there this month and “effectively disappeared into a black box,” the lawsuit says.

“This isolation is no coincidence. Guantanamo is home to one of the most notorious prisons in the world, used when the U.S. government has attempted to operate in secret, without legal constraint or accountability,” the suit says.

The lawsuit’s plaintiffs include relatives of three immigrants from Venezuela who were sent to Guantanamo from immigration detention facilities in Texas. The suit accuses government officials of violating their constitutional rights to due process and free speech.

The plaintiffs’ attorneys are seeking a court order allowing them to meet with the detainees. They also want an order requiring officials to provide the location of a detainee within 24 hours of their transfer to Guantanamo. The first U.S. military flight deporting migrants from the U.S. to Guantanamo landed in Cuba on Feb. 4, according to a U.S. official.