The Spanish monarch, who is resting in hospital after an accident on an elephant hunt in Botswana, is facing calls to abdicate over his extravagant expenditure.
Left-wing parties have heavily criticised 74-year-old Juan Carlos I for his lavish lifestyle, with many critics calling for greater accountability over the King’s finances.
Questions have been raised over the monarch's spending at a time when Spain is suffering a severe economic crisis, with citizens shouldering harsh austerity measures to abate the European economic meltdown that has so blighted Greece and other eurozone countries.
On Sunday, Tomas Gomez, the leader of the opposition socialist party, demanded the head of state choose “between his obligations and the duty of service of his public responsibilities, or an abdication that would allow him to enjoy a different kind of life."
Cayo Lara Moya, leader of the United Left Party, joined the condemnation, saying that the King’s action had showed “a complete lack of ethics and respect toward the people of Spain who are suffering a lot".
The beleaguered monarch has also faced criticism from animal rights groups, with his role as the patron of the Spanish chapter of the World Wildlife Fund somewhat jarring with a trip to Africa to kills elephants.
Finances published by the palace show that public expenditure on the monarchy was reduced by only 2% in 2011.