Some joker used prank website 12minutos.com to post an article (archived here) titled "URGENTE | BÉLGICA dicta una Orden Europea de detención para Mariano Rajoy". The full text of the hoax read:
La Justicia belga acusa al presidente del Gobierno español de corrupción, falsificación de documentos administrativos y delitos incluidos en la jurisdicción de la Corte Penal Internacional en relación a la aplicación del artículo 155 y encarcelamiento y exilio del Govern de la Generalitat de Catalunya
Translated (via Google Translate):
The Belgian Justice accuses the president of the Spanish Government of corruption, falsification of administrative documents and crimes included in the jurisdiction of the International Criminal Court in relation to the application of Article 155 and imprisonment and exile of the Government of the Generalitat de Catalunya
None of it is true. The site 12minutos.com is a prank website where users can submit their own headline, description and photo to create realistic looking prank news articles. It carries following disclaimer at the bottom of the page, informing people all articles are fictional:
Este es un sitio de entretenimiento, las noticias son creadas por los usuarios. Estás son noticias humorísticas, de fantasía, ficticias, que no deben ser tomadas en serio o servir como fuente de información.
Users don't even need to upload their own image, there is a built-in search function that will pull an appropriate image from Google image search.
The site is part of a larger network of prank sites all using the same basic layout but sometimes in different languages. It appears to be run by a Belgian company named Mediavibes or Media Vibes which is managed by a man named Nicolas Gouriou according to registration records.
So don't fall for this prank now that we've warned you about it!