El Salvador has agreed to house violent US criminals and receive deportees of any nationality, US Secretary of State Marco Rubio announced Monday, in an unprecedented – and legally problematic deal – that has alarmed critics and rights groups.

Rubio unveiled the agreement after meeting with Salvadoran President Nayib Bukele, as part of a tour of several Central American countries intended to consolidate regional support for the Trump administration’s immigration policy.

“In an act of extraordinary friendship to our country … (El Salvador) has agreed to the most unprecedented and extraordinary migratory agreement anywhere in the world,” Rubio told reporters Monday.

The country will continue accepting Salvadoran deportees who illegally entered the US, he said. It will also “accept for deportation any illegal alien in the United States who is a criminal from any nationality, be they MS-13 or Tren de Aragua and house them in his jails,” he said – referring to two notorious transnational gangs with members from El Salvador and Venezuela.