The US Homeland Security Department said on Tuesday a deportation flight carrying immigrants from different countries had landed in Eswatini, in a move that follows the US Supreme Court lifting limits on deporting migrants to third countries.

In late June, the US Supreme Court cleared the way for President Donald Trump's administration to resume deporting migrants to countries other than their own without offering them a chance to show the harms they could face. The decision handed the government a win in its aggressive pursuit of mass deportations.

"A safe third country deportation flight to Eswatini in Southern Africa has landed — This flight took individuals so uniquely barbaric that their home countries refused to take them back," US Department of Homeland Security spokesperson Tricia McLaughlin said late on Tuesday.

Earlier this month, a top Trump administration official said in a memo that US immigration officials may deport migrants to countries other than their home nations with as little as six hours' notice.

US Immigration and Customs Enforcement will generally wait at least 24 hours to deport someone after informing them of their removal to a so-called "third country," according to a memo dated July 9 from the agency's acting director, Todd Lyons.

The United States Immigration and Customs Enforcement (ICE) could remove them, however, to a so-called "third country" with as little as six hours' notice "in exigent circumstances," the memo said, as long as the person was provided the chance to speak with an attorney.

The memo stated that migrants could be sent to nations that have pledged not to persecute or torture them "without the need for further procedures”.

The new ICE policy suggested the Trump administration could move quickly to send migrants to countries around the world.

Human rights advocates have raised due process and other concerns over Trump's immigration policies that his administration has cast as measures aimed at improving domestic security.