Pedro Sanchez said the decision taken by the Royal Household was “fitting of a robust democracy”. Juan Carlos reigned from 1975 until 2014 when he abdicated. His departure – aimed at making his son, King Felipe’s reign easier after allegations of a scandal – was announced by the Royal Household on Monday.
Several Spanish newspapers have reported that he is heading to the Dominican Republic, though one placed him in Portugal.
Mr Sanchez told reporters at a news conference: “We declare absolute respect for what lies behind the royal household’s decision, which is to create distance from alleged questionable, reprehensible behaviour on the part of a member of the royal household.
“Institutions should not be judged, people should be judged.
“In this case, Juan Carlos has said clearly he is at the disposal of the legal system if necessary, just like any other Spaniard.
“I think the response is fitting of a robust democracy.”
The royal palace said the former king was leaving so that his personal affairs would not overshadow his son’s reign, in a statement that stunned Spaniards.
His abrupt departure has left Spaniards divided, with some accusing him of running away from his problems while others have demanded he return to face the music.
Prosecutors in Geneva and Madrid are investigating alleged financial misconduct.
Juan Carlos, who has repeatedly declined to comment on the matter, is not formally under investigation in Spain or Switzerland.
On Monday the ex-king’s lawyer said Juan Carlos was “at the disposal” of prosecutors.
Via his lawyer, the ex-king has repeatedly declined to comment on the corruption allegations.
Madrid resident Paz Rodriguez offered no sympathy for the former monarch.
He said: “I think he’s running away like a coward.”
Retiree Santiago Pradas was more understanding.
He said: “They’re not being fair.”