Washington DC - President Donald Trump asked the Supreme Court on Friday to overturn a lower court ban on his use of an obscure wartime law to deport alleged Venezuelan gang members without due process.

The emergency appeal sets up a showdown over one of the most glaring examples of Trump's unprecedented attempts to increase presidential power since returning to the White House in January.

Trump invoked the little-known 1798 Alien Enemies Act to justify rounding up alleged Venezuelan gang members, some of whom were sent to a notorious maximum security prison set up by the right-wing government in El Salvador.

The Trump administration has used images of the alleged Tren de Aragua gang members being shackled and having their heads shaved in the Central American prison as proof that it is serious about cracking down on undocumented immigration.

Donald Trump Trump attacks ex-special counsel who investigated Russia ties

Rights advocates say some of the deportees had nothing to do with gangs and that even potential criminals are required to be given court hearings before expulsion, in line with the Constitution.

District Judge James Boasberg issued an injunction barring further flights of deportees under the Alien Enemies Act after two planeloads of Venezuelan migrants were sent to El Salvador on March 15.

Boasberg said migrants subject to potential deportation should be "entitled to individualized hearings to determine whether the Act applies to them at all."

On Friday, the judge extended until April 12 his temporary restraining order barring any further deportations under the Alien Enemies Act.

An initial appeal by the Trump administration was turned down Wednesday with one appeals court judge saying that even "Nazis got better treatment" from the US during World War II.

In its appeal to the Supreme Court, which is dominated by conservative justices, acting Solicitor General Sarah Harris said the case is a key test of presidential authority over the courts.

"This case presents fundamental questions about who decides how to conduct sensitive national-security-related operations in this country" – the president or judges, Harris said.

"The Constitution supplies a clear answer: the President," she said. "The republic cannot afford a different choice."