WASHINGTON, May 10, 2025 (BSS/AFP) - Four US advocacy groups said Friday they have asked the Inter-American Commission on Human Rights to intervene in the detention of migrants who were deported from the United States to a mega-prison in El Salvador.

Acting on behalf of families of more than a dozen deportees, the groups are seeking precautionary measures to stave off "irreparable harm," said Blaine Bookey of the Center for Gender and Refugee Studies at the University of California San Francisco.

In March, US President Donald Trump invoked the 1798 Alien Enemies Act to send alleged members of the Venezuelan gang Tren de Aragua to a massive prison, CECOT, in El Salvador.

The US Supreme Court and several lower courts have since temporarily halted deportations using the obscure law, citing the lack of due process.

"There are about 288 people, but since everything is so opaque and there is no transparency, there could be more," Isabel Carlota Roby of Robert F. Kennedy Human Rights told AFP.

She added the groups were seeking quick action from Washington-based IACHR "because the situation is serious and imminent."

Under Trump's use of the Alien Enemies Act, migrants have been accused of gang membership and sent to El Salvador without going before a judge or being charged with a crime.

Bookey said IACHR's recommendations are not binding but El Salvador has obligations under regional human rights conventions to which it is a party.

The other groups in the appeal are the International Human Rights Clinic at Boston University and the Global Strategic Litigation Council for Refugee Rights at Cornell University.